You'll have to use the AppLoader in BBDM. Application data database will contain all downloaded PB applications if you back it up or restore. If this database is not backed up the applications downloaded to the BlackBerry PlayBook tablet can still be retrieved from BlackBerry AppWorld. You can read more in this article.
DM can do selective backups and that could include Apps. But if you purchased them or they were free and there's been no Price Change, you can download again from appworld. If there is a change in price, you might have to make up the difference if you don't have your own backups.
