Code:
# seq 1 100 | awk '{ if (NR % 5 == 1) {print "mynewfile.mp3"}; print}'
mynewfile.mp3
1
2
3
4
5
mynewfile.mp3
6
7
8
9
10
mynewfile.mp3
11
12
13
14
15
mynewfile.mp3
16
17
Just something like that? Change the 5 to 25 in your case, and feed it the playlist instead of a seq.
NB. This will not work with Ska though and Ska is F£$%^ing awful. :P