The question how to move your existing Stage Traxx library to a new iPad pops up quite often. So here are the possible ways to achieve this.
Using iTunes Backup
The easiest way is to create a backup of your old iPad in iTunes and then restore the backup on your new iPad. Apple has good documentation on how to do that: https://support.apple.com/en-us/HT201269
Please do also sync your iTunes songs back to the new iPad. If you always work with local files in Stage Traxx, this step is taken care of by the iTunes backup.
Once this is done, you can start Stage Traxx.
Using Stage Traxx Backup
You can create a backup file in Stage Traxx on your old iPad and transfer it via Dropbox or iTunes Filesharing to the new iPad. If you use local files in Stage Traxx, please copy them via iTunes Filesharing to the new iPad. If you use iTunes songs, transfer them to the new iPad via iTunes.
Once your songs and the backup are transfered, open Stage Traxx and restore the backup.