A 42-year-old woman with myasthenia gravis (MG) undergoes laparoscopic cholecystectomy. Anesthesia is induced with propofol and remifentanil; succinylcholine is avoided. Rocuronium 0.6 mg/kg is given for intubation. Intraoperatively, train-of-four monitoring shows progressive fade (TOF ratio 0.4 at 90 minutes). The surgeon requests one more 15-minute interval for hemostasis. What is the most appropriate management?