Some examples of poems with repetition are Edgar Allen Poe's "The Bells" and "War is Kind" by Stephen Crane. A single word, whole lines or stanzas, or the beginning and ending words are repeated throughout each poem.
In "The Bells," the word "bells" is repeated and gives the vision of bells ringing. This type of repetition creates a rhythm.
The line "Do not weep. War is Kind." is repeated in "War is Kind" to emphasize that war is really not kind. This is illustrated by the rest of the poem, which explains that people died as a result of the war.