Hmm. Just how many organic items are out there?
The only one I can think of offhand is a thin layer of extra muscle, for which I might recommend the skill "Massage Therapy"

Perhaps the skill "rejuvenate"?
It might not be a bad idea to have an organic fixing skill, but you may want to extend that skill to clerics, whom are healers, afterall. Not to say that class isn't powerful enough already, but perhaps from an RP standpoint, it would work.
On the other hand, There probably should be items that cannot be repaired, because they're priceless. Frankly, if an item is organic, it should have a finite lifespan. I don't believe anything in the game is blessed with immortality, except for staffers!