A 62-year-old woman with rheumatoid arthritis has been taking naproxen 500 mg twice daily for 8 months. She presents with epigastric pain, nausea, and melena. Endoscopy reveals a 1.5 cm gastric ulcer with active bleeding. Her hemoglobin is 8.2 g/dL. She denies Helicobacter pylori infection (serology negative 2 years ago) and is not on any gastroprotective agent. After hemostasis is achieved, which of the following is the most appropriate long-term strategy to prevent ulcer recurrence?