Here's my example. My hero has been ruminating about his move to a new village. I wanted to get the point across, without revealing too much information, that there is something in his past that is painful to him, something he wishes he could forget. Here's the last two sentences of the scene:
. . . his heart stirred in a way he hadn’t felt in years, not since—he’d rather not remember when. He came here to forget. Oh, God, help me forget.
It's not brilliantly profound, but the repetition of the word "forget" is still pretty powerful. It's also the last word in that scene, and I'll make a point about that later.
Here's another example of how I used repetition during what I hoped was a poignant moment.
If he loved her, truly loved her, he’d help her. He’d send her to the abbess with money and papers that would serve . . . to lock her away from him forever.
He forced himself to breathe past the pain, the pain of living without seeing her again. The pain of loving her too much.
I hope the repetition of "the pain" gets my point across poignantly.
On Friday I'll post some awesome examples from the great writer of children's fiction, Kate DiCamillo. She is a master at powerful repetition.