Do I need a lift if I want my implant over the muscle? (Photo)

I had my 1st breat augmentation 21 years ago .400 cc mentor saline implant over the muscle .Was really happy with my result (round fake look).i hade 2 pregnancies after and breast got bigger and move to the side when i lay down. Do i need a breast lift if a i want my implant over the muscle again and do i need to go bigger implant for the round fake look