For user data, as long as the migration you did of core Joomla content kept the jos_user table completely intact (mainly the 'id' for each user), you can just transfer all of the jos_jfbconnect_... tables to the new installation. Install the JFBConnect v2.5 version and everything should just work using your old configuration and user's won't see the difference.
As for profile data, that's all stored in separate extensions (JomSocial, CB, etc), so if you upgraded those, the data should be there.
Alex
Migration 1.5 - 2.5
