This answer may be found in the 2012-13 college catalog on page 11.
"If you retake a course for which you have already received a grade, the later grade will be transcripted and used in computing your grade point average (GPA). The earlier grade is removed from computation of the earlier term GPA and the cumulative GPA. You will be allowed two retakes to improve your grade. Subsequent retakes will be transcripted, but may not be used to meet degree requirements."