In music, a refrain is a passage that we return to rather than continuing to progress the song. When we hear refrain as a verb, the metaphor tends to focus on t

In music, a refrain is a passage that we return to rather than continuing to progress the song. When we hear refrain as a verb, the metaphor tends to focus on the "abstaining from something else" aspect, but here she's focusing on the "repeated passage" aspect. It's not a common use but it basically works.