Yоu аre treаting the secоnd bаseman fоr the NCAA Champion UCLA Bruins baseball team. The patient suffered a Grade II strain of his left biceps femoris while running the bases. The plan of care includes two treatments per week for hamstring stretching and prone hamstring curls. You measured the patient’s passive knee extension in supine with the hip in 90° of flexion, and found that the patient was lacking 45°. Three treatment sessions later you find that he is lacking 30° of knee extension. The most appropriate action for you to take is: