According to Osho, the Gita repeats because awakened ones hammer with pauses to rouse our sleeping consciousness. Continuity dulls; intermittent reiteration hits fresh, like an alarm or dripping water. The repetition is not Krishna's limitation but Arjuna's unreadiness. Since our inner weather keeps changing, the same truth must be restated so it lands when receptivity peaks and the wires connect.
Great teachers repeat because we are often sleepy inside; the same simple truth must be heard many times until it reaches us at the right moment.