If you created the Arp in the MODX you can save that data as a .mid file.
The Arp data is NOT stored with the Performance, what is stored with your Performance, for example, is that you used USER ARP #001.

User Arps (as many as 256 of them) are saved to the User File (.X8U). If you wish to share them with a friend, you’ll need to either send them the .mid file used to create them (and they can create their own User Arp from that data) or you can send them a MODX User File .X8U that contains your User Bank data.

Extra Credit:
Your current custom USER Bank data can be reviewed by going to the Data Utility Folders:
[UTILITY] > “Contents” > “Data Utility” > there are Folders here for your current User Arps, Live Sets, Motion Seqs, Patterns, Performances, Songs and Waveforms. Tap the Folder to view its contents.

thanks for the clarifications,