Lesser (and possibly) greater reincarnations with no level changes should have a much shorter cooldown.
Feat / Spell / Enhancement swaps and respecs are 3 days
Make a vanilla Lesser 4 days
Then add 1 day for each + of the reincarnation...so a Lesser +1 would be 5 days, etc.

This would serve to help those trying out a new class to try out a variety of builds a bit quicker...especially those feat starved classes that someone might be trying to find a good fit to their own playstyle with.