Exercises for Tightening Pectoral Muscles After Breast Implants?

Unfortunately there aren't any exercises that lift breasts, whether there are implants or not. It is possible though that using your pectoral muscles will push the implants down over time, which may or may not look better.

Pectoral muscle tightening will not lift breasts. In fact, it is wise to proceed with exercise only with your surgeon's knowledge and approval. Consult with your surgeon as he or she knows the scope of the surgery and the specifics about you.

Oki,
No amount of pectoral muscle development will lift your breasts.  In fact, it might even worsen the sagging appearance.  Let your implants settle a bit longer, about six months, before you decide whether a lift is in order.  Good luck!