A 72-year-old man with COPD (FEV1 45% predicted, GOLD stage 3 equivalent) has had three moderate exacerbations requiring prednisone and antibiotics in the past year despite being on dual long-acting bronchodilator therapy (LAMA/LABA). He continues to smoke. According to the 2023 Canadian Thoracic Society COPD pharmacotherapy guideline, what is the next best step?