To do again what was done. Repetition is how a thing becomes a practice, and how it becomes a rut.
Latin repetere (to seek again, to attack again): re- (again) + petere (to seek, to aim at); repetition is a seeking done more than once, and whether it becomes practice or a rut depends entirely on what is sought.
To do again what was done. The root's seeking-again is neutral about outcome: repetition is how a thing becomes a practice, and it is exactly how it becomes a rut.