Take her to the vet to insure that the vomitting isn't from a serious condition. Maybe it's the type of food you are feeding her or even the amount. My cat used to throw up when we'd feed her a little too much because she'd scarf it all down very quickly. Try portioning the size a little less to give her tummy a break. Good luck:)
also make sure she isn't eating grass or plants, they can make a cat throw up. if not, try giving her some, it can help with digestion and metabolism! :) (teehee that probably made no sense but trust me - I know cats)