A 66-year-old man is admitted with melaena from a duodenal ulcer and undergoes successful endoscopic haemostasis. He has taken aspirin 100 mg daily since a myocardial infarction three years ago, with no coronary stent and no other antithrombotic indication. His haemoglobin is stable 24 hours later and there is no further melaena. Which one of the following is the most appropriate plan for his aspirin?