Have you tried cycling them? Just charge them, and run them down, charge them, run them down...

Just do it every day a few hours straight (at least through 5 cycles), Ive got some old packs here that Ive bene working on for a few months (not straight though, just here and their). They started out only holding like 300-500mah, but now theyre holding like 1000+mah (which is a little over half their capacity).