Hello reesababy28
No, technically you do not have to retake the exam. You do have the option to retake if you would like to try and get a higher grade (ie: 95, 100). The higher of the two grades will count. For example, if you get a 90 on your first "try" at the exam, and score a 100 on your retake, the 100 would count. I always retake the exam if I don't get a 100. It doesn't hurt, it can only help.
Do note though, that the retake exam will not be the exact same exam you just took. It may or may not include the same questions. I hope this helps! Good luck on your Journey!