A 38-year-old woman with a 5-year history of secondary infertility undergoes diagnostic laparoscopy, which reveals stage III endometriosis with adhesions and a 3 cm endometrioma on the left ovary. Her husband's semen analysis is normal. After surgical excision of the endometrioma and adhesiolysis, the couple attempts natural conception for 12 months without success. Repeat semen analysis remains normal. Transvaginal ultrasound shows no recurrent endometrioma. What is the most appropriate next step in management?