The catalog outlines specific language for the Loading... policy.
Any student, undergraduate or graduate, who wishes to repeat a non-repeatable course, will receive an error message while trying to register. Before registration can occur, the student must receive an override from their major advisor or graduate group coordinator.
If this is your third attempt of the course, you will need to contact the school or program that offers the course you wish to repeat. They will provide further instructions about the correct process to obtain permission (in the form of an override), if approved.