Repetition is a second assault. The word repeat comes from Latin repetere — 'to seek again, to attack again' — from re- ('again') and petere ('to rush at, to seek, to aim for'). When a Roman orator repeated a point, the metaphor was military: he was attacking the audience's resistance a second time.
Latin petere is one of those roots whose original violence faded into abstraction. It meant 'to fly at, to rush towards, to attack'. From this came compete (to seek or strive together), petition (a formal seeking), appetite (a seeking towards food, from ad- + petere), impetus (the force of rushing at something), and perpetual (seeking through without end).
French répéter preserves a meaning English repeat has mostly lost: to rehearse. A French actor who répète is practising a role — repeating lines until they are perfect. English uses repeat more narrowly for simple recurrence.
The noun repeat appeared in the 16th century. A repeat performance, a repeat offender, a musical repeat — all describe something that happens again. The military edge has entirely vanished. Yet the structure of the word still holds: re- ('again') and a verb of directed motion. Repetition is forward movement, renewed.
The connection between repetition and learning is ancient. Latin itself used repetere for going back over lessons. To repeat is to seek the same ground again, and in that second seeking, understanding deepens.