University policy states that you may NOT for any reason retake a course if you have made a C- or better. 

Even if a student makes below a C- in a course and must retake it, no student may enroll in the same Natural Sciences course more than twice without permission from their advisor. Therefore, students taking a Natural Sciences course for a second time need to be aware it may be their last chance to pass that course. You may only repeat a CS Entry-Level course (CS 312, CS 313K/311, CS 314, M 408S/L/D) one time, no exceptions. Students may fill out a third time repeat appeal to take a CNS class for a third time that will have to be approved by an advisor. These appeals will not be approved for Entry-Level CS courses.