A person underwent laparotomy for Crohn's disease with melena. A 15 cm segment of ileum was found to be diseased. Segmental resection with healthy margins and end-to-end anastomosis was done. On 7th postoperative day, the patient developed anastomotic leak. He continued to have 150-200 ml fistula output for the next 7 days. There was no collection of fluid in the abdomen and now patient is stable. The ideal management is: