Repair and Reinstall (ie. uninstall and then reinstall again) are not supported on the comming Beta2 of Visual Studio Team Foundation. If you want to reinstall or repair your application and keep your existing data, you will need to backup the data first, and then reimage the machines and install from fresh again, then restore your data on the databases.
The work to fix the repair / reinstall scenarios is going to be after beta 2. I am talking only about Visual Studio Team Foundation Application Tier and Data Tier installs. (both on different machines or on a single machine).