Is there a method to reflect a spell back at it's caster..
Say a ReVi effect ???
Thrumbar 
I'd say no, as it sounds a bit too much like magickal resistance in spellform... maybe sith a Hermetic Breathrough though. The effect is not listed in the AR0205.
You'll just hafta kill 'em afore they kill you 
It looks like you could change the target of a formulaic spell with a fast-cast MuVi spell-- the guideline to "significantly change a spell" mentions a change of target. So, I would think you could just change the target to the spell's caster, who is certainly in range. I think there used to be a spell that did this, but it doesn't look like it made it into Fifth Edition.
I agree with the other Erik.
A spell that was range voice target individual duration momentary could turn a spell of up to 1 magnetude lower than itself back at the caster. A character could spont it or master it for fast casting.
That'd certainly be possible... it would have to be one for each Form though. So ten mastered spells of relatively high magnitude. There is also another solution; the spells you most want to avoid would be the damaging ones mayhaps? So use ReIg, ReTe, ReAq, ReHe etc to make any damaging effect "bounce back" so to speak. Almost like the wards, but with an added something extra. Not sure if that'd be workable for every type of spell though.
An interesting question is: can you give a spell in an invested device a higher initiative or fast casting? There are no official rules... but what do you think? +3 Level for every Ini Bonus or +15 for fast-casting?
/e Not a ReHe/ReAq/ect Spell, a MuVi Spell with no requisite but an extra spell for every form.
I'd go with the form specific spells as well despite this not being crystal clear from the guidelines. Perhaps a spell that could target any form would need to double the level of the target spell, similar to the perdo vim dispelling guidelines.
IIRC, there is a prohibition against changing a spell once its cast...so changing the target once someone cast it is impossible.
If you are talking about changing the spell that someone is casting at you, I would guess you need to see M/V guidelines and a couple of those spells.