So... I kind of feel like I am heading toward burn out. With the game so focused on fights I worry that all of my fights are starting to feel the same. I feel like I spend a lot of time making the bad guys but then all the bad guys are really exactly like all the other bad guys I have made.
Does anyone have any suggestions that will help keep things fresh for both the player and the GM?
I've had an ongoing Feng Shui 2 campaign for about a year, something like 25 sessions or so. I can sympathize!
Have you been focusing on a single Juncture?
In my game I find we get a lot out of the variety provided by different Junctures. They'll spend several sessions engaged in subtle intrigue and sophisticated espionage in Eastern Europe, using technology and seduction to fight modern bad guys who use guns. Then they'll go to the Ancient Juncture and fight evil flying kung fu cults and sorcerers who raise the dead and send demons after them. And then they'll be in the Past Juncture fighting martial artists who use pressure point kung fu techniques learned from ancient scrolls. Then they might go to the Future Juncture and have car chases with souped-up scroungetech cyborgs.
Not to mention the Netherworld, where all these things could happen simultaneously!
You can also look at the objectives of your bad guys. Maybe one adventure involves preventing the Eaters of the Lotus from acquiring several specific feng shui sites they need to cast an elaborate spell to raise Qin Shi Huang's terracotta warriors from their tombs beneath Xi'an so they can destroy Emperor Wu Zetian. That's a huge thing, affecting a million people in Xi'an and potentially deciding the fate of all subsequent Junctures.
Then maybe follow that up with an adventure involving a long-lost relative of one of your characters coming back, maybe having turned evil and wanting to harm the hero. The adventure could have a small, intense scope, where it's not about a huge climax but it's about the relationship between these two people and the circle of friends around them.
Then maybe go medium-big on their next adventure. Have a feng shui site that's important to your characters under attack, and the heroes need to protect it.
Switch between factions for each adventure (with an adventure spanning perhaps 2 or 3 sessions), keep larger plots going in the background. That can help create a sense of variety.
For more variety on your bad guys, try making sure they are different in as many ways as you can from the previous big bad:
Age: One bad guy could be a demon thousands of years old, another could be a powerful young kung fu fighter who stumbled across an ancient scroll and betrayed his master.
Gender: Have a good mix of male and female villains. I even took a cue from wu xia movies like Swordsman or The Bride With White Hair and had a boss who switched genders on every shot. The female side used ranged attacks and sorcery, the male side used melee kung fu.
Faction: Definitely throw all the factions into the mix and keep things changing. If you've got a long-running series of battles against The Ascended, give the Eaters of the Lotus or the Four Monarchs of the Netherworld some love!
Status: High status versus low status. High status villains are rich, powerful, mob bosses, Netherworld monarchs, kings, emperors, etc. A low status villain could be someone trying to rise up, maybe a member of the Ascended or the Jammers who's trying to strike out on their own. It's the difference between somebody who expects everything handed to them versus somebody who has nothing and will try anything to get ahead.
Race/Nationality: Give your next bad guy a different race or nationality than your last. If the last one was a Chinese triad boss, maybe the next villain is a British member of the Ascended, or a Japanese samurai lord, or a Thai martial artist, or an American military leader.
Motivation: What kind of motivations do your bad guys have? Are they all trying to just kill people and take over the world? That's great every now and then, but do something different for your next bad guy. Maybe they have a sick daughter and they're trying to take over some important feng shui sites and kidnap expert doctors to improve her chances of getting better.
Schemes: Mix up the kinds of schemes your villains engage in. Follow a sneaky conspiracy that takes months to fully uncover with a brute-force attack on civilians, robbing banks or kidnapping people.
Underlings: What kind of underlings to your villains have? Some bosses might have a long stream of relatively low-level featured foes, along with hundreds of mooks. Others might have only a couple of VERY tough enforcers, and use relatively few mooks.
Technique: Of course, this is a big one. In Feng Shui 2 there are Guns, Martial Arts, Sorcery, Scroungetech, Mutant types of attacks. If your last bad guy was a Guns user, make the next one a Martial Artist or a Sorcerer.
Hope some of this helps!
Can I also suggest some good old fashioned action-film-watching?
Watched Die hard last night (our tribute to Mr Rickman), boy that film has some good action scenes. 
However, a week or so ago I watched the prequel Detective Dee film, that first(ish) fight scene really gave me some ideas for our next fight scene (hope my players aren't reading this). Basically, one of my players may or may not (as I don't like to force scenes on players, so they can avoid if they roll/describe well enough) end up stuck inside a crate of some sort while mooks and assorted featured foes stab at it with swords.
I suppose, looking at that fight scene (you'll know which one I'm on about if you watch the film) it would also be a good intro for a Supernatural Character PC.
Looking at my previous post, I think I might be addicted to smiley faces.
...Had to really put some effort into not putting one the end of that last sentence.
......and that one...
ARRRRRH!!! MUST RESIST!
I too watched Die Hard and got loads of ideas. Such a great movie!
I also think I prefer the Detective Dee prequel to the Andy Lau one. It's amazing!
Thanks for the advice!
I have sort of realized that the game just doesn't work 100% for my group. We have had a good time with it but because combat can take a good chunk of time and our sessions are rather short compared to the good old days when we would stay up all night gaming (getting old and being responsible kind of sucks) we will likely complete our current story and then move on to another game.
I guess in the end i simply need more mechanical diversity in my bad guys to keep them interesting and the game is really not about them being all that mechanically diverse.
Much of the diversity is in narrative/description, which includes schticks and stunts. It's not that much different from how the fiction provides diversity in games like D&D, which are also fairly repetitive (roll, hit, damage, roll, hit, damage). Introducing a variety of fight locations, motivational hooks, dialogue, and other things that don't actually require any mechanical differences can make FS2 fights seem quite different from one another.
Remember, in RPGs, if you just ignore all of the fiction it's just a bunch of numbers moving around assigned to decisions without context. We want to always provide that context, and the game does that to some extent, but the players and GM have to do their fair share of the lifting as well.