That data is stored in the 'user' table within the DB. You might be able to achieve what you want by backing up the db file [1] and then copying it back in after your new install.
I can also think of some ways to achieve this using the db.view [2] but that is probably rather advanced and I don't know if that interface allows multiple commands at a time.
[1] Location, and possibly name, might vary between OSes, I think in Ubuntu by default it is: /var/subsonic/db/subsonic.data
[2]
https://sourceforge.net/apps/mediawiki/ ... e=Database