Is there a process for replacing tiles in orbit?

Here is a scenario that, given the repeated damage to the tiles at launch, seems quite likely: The shuttle launches, and yet again foam damages the tiles- however this time the damage is clearly too severe for re-entry. The astronauts are forced to use the ISS as a lifeboat, and return via the soyuz REVs...

I know that the tiles vary in shape and function so carrying a complete set of spares is not an option, so a new crew is sent up with replacement tiles for the damaged section- is it possible that they could replace tiles in orbit? Or is the shuttle just doomed?

What if the damage is borderline for re-entry, can the shuttle be remotely piloted for reentry?