Traditionally, in American pop music, the core of the song is considered to be the vocals/lyrics. Therefore if you keep the vocals and change the instrumental, it's a remix. New lyrics and vocals over an existing instrumental would be considered a derivative song, or possibly a brand new song sampling the old song (although you wouldn't typically use the ...
The personnel is:
Dave Bickler – lead vocals
Frankie Sullivan – lead and rhythm guitars, vocals
Jim Peterik – grand piano, electric guitar, vocals
Stephan Ellis – bass
Marc Droubay – drums
There are plenty of remixes, your favorite search engine will list them for you.