Data Backup and Restoring the same if requried in SQL SERVER 2008
You can't without export/import.

A single, shared database implies all data is linked and requires full transactional/referential integrity. So the standard backup/restore won't work because you can't cleanly (or at all?) do row-level partial actions.

You're export/import needs to be transactional safe too, and foreign keys need considered

To make things simpler, you really need a database per tenant.
See Decision criteria on when to use a non-dbo schema vs a new Database for more discussion
If you can't, then you have to live to export/import