Lose bodyfat. I know a girl who, after completing contest prep for a major southeastern NPC competition (with AAS) went from a D to an A, and then got a boob job to get back to a D.
Does your g/f want to drop her breast size? If she wants to do it, what are her current stats (weight, bodyfat%)? Does she train? What is her diet like? Basically if she wants to drop some % bodyfat, part of it will come from the girls.