"
And my head is going bum bum de de de de pum pum
Turn it up and blast the- blast the beat
When you are at a party, your heart seems to beat louder and closer to the sound of the music, and this is what she was emphasizing in the song. Her own heart, in the song, was beating to the sound of the party music and she could hear it beating (or at least feel it). Your head seems like the same thing, and China Anne McClain was emphasizing this by using repitation. The line "Turn up and blast the-blast the beat" explains that she was allowing the music to keep out her feelings about the date that never came.