njc235 your purchase will be restored without a charge, just follow the process.
Having your songs on your Mac to restore your iPad,
well it depends how you stored them , did you make a full backup of the iPad then stored that on your Mac?
Or, do you also have ST3 on your Mac with all the songs you need in it?
Or do you just have all the songs on the Mac only with no lyrics or timestamps , if this is the case you are in trouble as you will have to redo all the lyrics and timestamps once you get your iPad back, lets hope this is not the case.
If you have all the songs in ST3 on your Mac , just make a full backup in settings , copy this backup to your new iPad ,then restore this backup and you are all done.
If you have a full ST3 backup already on your Mac , then just copy it to your fixed iPad and restore it.
If you just have all the songs in a file on Mac, then just copy them and place them in to your ST3 folder of your repaired iPad , then go to ST3 song mode and pull the song list screen down to refresh your library , now you will have all your songs back , but now you have a long task of entering song lyrics , time stamping them and creating audio segments, good luck with that , always make a full backup and store it in and on different places to save yourself a lot of unnecessary work.
Cheers Damir