Both options are acceptable
The initial pathology report of the biopsy sometimes comments on whether the abnormal cells are at the margin or if it is clear. if it is questionable, then further excision is prudent although not urgent with only mild-moderately abnormal nevus cells. Certainly "watchful waiting" in the setting of moderate dysplasia that may already have been completely removed is quit reasonable. You and your Dermatologist would then commit to a follow up exam in 6 months - 1 year to check the biopsy site. Recurrent pigmentation is a good indicator that the nevus cells are still there and then you can proceed with reexcision at that time.