How is it possible to prevent melanoma from recurring?

Surgical Technique. The best means of preventing a melanoma from recurring locally is to have your surgeon perform an appropriate wide local resection. By taking a margin of normal skin around the melanoma you reduce of the chances of it coming back.
Early appropriate Rx. The best way to prevent a melanoma from recurring is to have it treated as early as possible by an experienced physician who performs the correct definitive surgery. There is no magic medicine that will reliably prevent melanoma recurrence, nor does sun avoidance prevent melanoma from coming back.
Appropriate therapy. Early detection and appropriate treatment is important. Surgical excision of the primary lesion is always indicated, and biopsy of local lymph nodes and/or sentinal nodes can be helpful if the melanoma is deep enough. If you have been diagnosed with a melanoma make sure you are treated by a multi specialty team with experience in melanoma.