How to plump up the butt?

this sucks, I've lost a good amount of weight for my height with a combination of weights and cardio so I'm slightly toned, but not a lot. Now I can say I'm happy with how I look (with of course more toning) but now my butt looks like it's flattening! I've always kinda had a plump butt but that was from gaining weight. How can I plump it up? I do lunges and squats every other day. I do two sets of twelve, should I just do them more often?