What phrase suggests the need to repeat an exercise?

The phrase "do it again" clearly indicates the need to repeat an exercise. It explicitly instructs someone to perform the action once more, implying that the previous attempt was either incomplete or unsatisfactory. In contexts such as practice routines or learning exercises, this command is commonly used to reinforce skills or clarify mistakes.

The other phrases convey different meanings; "give it a rest" suggests stopping or taking a break from the activity, "move on" implies that it's time to proceed to a different task or subject without revisiting the previous one, and "let it go" encourages someone to dismiss or forget about the matter entirely. Therefore, the phrase that best signifies the requirement to repeat an exercise is indeed "do it again."