A 62-year-old male with COPD (FEV₁ 55% predicted) on dual therapy (LABA + LAMA) presents with 2 exacerbations in the past 12 months requiring oral corticosteroids and antibiotics. He has a 40 pack-year smoking history and continues to smoke. Current symptoms include persistent dyspnea and productive cough. What is the most appropriate next step in management?