A 28-year-old woman with a 2-year history of recurrent cough and dyspnea presents to the pulmonology clinic. Baseline spirometry shows FEV1 of 65% predicted with FEV1/FVC ratio of 0.68. She is then administered 400 μg inhaled salbutamol via spacer (4 puffs separated by 30 seconds), and repeat spirometry is performed 15 minutes later. The result marked **B** in the diagram shows an increase in FEV1 of 18% from baseline with an absolute increase of 280 mL. Which of the following is the most appropriate next step in management based on this bronchodilator response?