Symploce

repetition of the first and last words in a sentence in following sentences. 

Ex. "Much of what I say might sound bitter, but it's the truth. Much of what I say might sound like it's stirring up trouble, but it's the truth. Much of what I say might sound like it is hate, but it's the truth." - Malcolm X

Source: http://www.americanrhetoric.com/figures/symploce.htm