You don't need to do anything to 'em, IMO! But...
As a woman with big natural jugs, I would give just about anything to have them smaller...so I am not going to be voting for larger. Just remember, gravity is a MF'er and they are one day going to head South, and require more surgery to get those puppies off the floor.
My vote is for a lift if you are just Hell-bent and just HAVE to have something done to them. I am a 38DD and I look forward to getting a reduction one day. I always have to wear a frikkin bra, dresses fit weird on me because I have to buy two or three sizes larger just to fit the girls in. They get in the way. I envy chicks that can run around bra-less. Bitches!