A 58-year-old male with a history of myasthenia gravis (MG) is scheduled for elective cholecystectomy. During induction, propofol and remifentanil are used. For muscle relaxation, a non-depolarising agent is chosen. Thirty minutes into surgery, the neuromuscular monitoring shows a train-of-four (TOF) ratio of 0.35 (moderate blockade). The surgeon requests deeper relaxation. The patient's last dose of pyridostigmine was 8 hours ago. What is the most appropriate next step?