A 72-year-old woman with known heart failure (NYHA Class II) presents with a 3-day history of increasing ankle swelling and shortness of breath on minimal exertion. Her current medications include Ramipril 10mg OD, Bisoprolol 5mg OD, and Spironolactone 25mg OD. Her renal function and potassium are stable. What is the most appropriate next step in managing her fluid overload?