General synonyms:
* Reiteration: to say something again, especially for emphasis.
* Redundancy: the state of being repetitive or unnecessary.
* Duplication: the act or process of making an exact copy.
* Recurrence: the act of occurring again.
* Iteration: the act of repeating a process.
* Echoing: to repeat something like an echo.
* Rehashing: to present something again in a new or different form.
More specific synonyms:
* Repetition: to say or do something again and again.
* Rehearsal: to practice something by repeating it.
* Imitation: to copy something exactly.
* Replication: to make an exact copy of something.
* Playback: to play something back again.
* Recycle: to use something again after it has been used once.
The best synonym to use will depend on the specific context of your writing.