A 28-year-old woman from Delhi presents with recurrent episodes of angioedema affecting her face, lips, and throat over the past 6 months. She denies urticaria. On examination, she is afebrile with normal vital signs. Serum C1 esterase inhibitor (C1-INH) level is 15% (normal 50–150%), and C1q level is normal. What is the most appropriate next step in management?