Let's say the song name ist SongXYZ.
1. You add the SongXYZ at the TOP of the playlist.
2. Now add other songs to the playlist, no matter how many - your choice.
3. Put the SongXYZ the SECOND time on the playlist, but this time at the very end of it.
4. You're done - when the playlist comes to its end, it will simply repeat from the beginning, because the SAME song is twice there and it always chooses the first!
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Example, how your playlist could look:
SongXYZ
Song1
Song2
Song3
Song4
Song5
...
SongXYZ
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Screen:
