A 38-year-old man with schizophrenia has been on risperidone 6 mg/day for 8 months. He presents to the psychiatry clinic with complaints of bilateral breast enlargement and galactorrhea for the past 2 months. Serum prolactin is 85 ng/mL (normal <25 ng/mL). He is otherwise clinically stable on his current antipsychotic regimen. What is the most appropriate next step in management?