If you want to continue this course, you need to re-enroll before the end of the month.

re-enroll 由前缀 re-（表示"再次"）和动词 enroll（注册、报名）组成。re-enroll 的意思是"重新注册"或"再次报名"，指之前已经注册过但需要再次办理注册手续。