I have read that if you rest that you get ability scores back, I do not know the length of time need to rest, also restoration potions work, I think the only permanet drain is level drain which you will need a restoration spell, potion, or wand for.
You will regain 1 attribut point for each rest, so it takes pretty long. But as someone else pointed out, since time isnt the matter, its the best poor men's restauration ability. I'd suggest to keep portions / wands for later combats, since you might need to regain your strength during an attack later.
