You've probably heard this before: read your work out loud. Most editors would encourage you to do so.
Once, a writer sent a nice poem to Kid's Imagination Train, but she repeated a phrase three times in two stanzas. The repetition in this piece was distracting and it caused the poem to weaken.
Had she read her work aloud, she would have caught this slip. Then, she could have used a thesaurus to find words to replace the redundant phrase.
There is an exception to using repetition. If you want to draw attention to a word for emphasis or for humor, then words and phrases can and should be repeated. A classic example is Green Eggs and Ham by Dr. Seuss:
Sam I am.
That Sam-I-am!
That Sam-I-am!
I do not like
That Sam-I-am!
Do you like
Green eggs and ham?
I do not like them,
Sam-I-am.
I do not like
Green eggs and ham.
Take a careful look at what you have written. Review it multiple times. Then close the door if you want and start reading it out loud to the computer screen. You can print a copy and read to a mirror or even read to your pet. Listen for any unintended repetition. Check to see if you work flows off your tongue. Catch awkward phrasing. I urge you to do this every time before you submit your work. And so, allow me to repeat myself: read your work out loud:)