A 30-year-old woman with a history of perianal Crohn’s disease has had a seton in place for transsphincteric fistula for the past 2 months. She is also taking infliximab for medical management of her Crohn’s disease with no active proctitis seen on recent endoscopy. Ultrasonography shows 50% involvement of the sphincter complex with no undrained abscess or high blind tracts. What is the most appropriate management approach for her fistula?