There are various studies about the use of chemotherapy early in the treatment, look for doublet and triplet therapy.

From my laymen's understanding, there are some PCa cells which are adaptive and do not respond (die...) to the low testosterone environment created by the use of monotherapy, in your case Lupron. Those cells may however, be "killed" by chemotherapy.

Discuss with your medical team, if you are physically and medically able to go through doublet or triplet therapy, it could be n option for a more durable remission.

Kevin