What do you mean by "backup" ?
Are you looking for:
- a Backup tool like
Abakt in order to backup your Liberkey (personnaly, I prefer to simple "copy/paste" Liberkey folder into another (backup) location... simpler is easier...)
- because you loose your Liberkey menu, you need to restore an old version of it ? (backup files with extension .xml are located in "bak" folder here: Liberkey\LiberKeyTools\LiberKeyMenu\data\bak)