While each school may have its own policies on retaking courses, typically you can retake a course to improve your grade. If you retake one, your most recent attempt will be used to calculate your GPA. All other attempts will remain on your official transcript but will not be used in GPA calculations. If you got a low grade in a required course, retaking it is a good way to improve your score. However, since your most recent score is the one that counts, you want to ensure you do better the second time around. Otherwise your repeated courses will lower your GPA instead of raising it.