Hi from Spain.
If I have not misunderstood you, an external linked file containing you site has dissapeared or being damaged.
In my opinion, my first option would be recover a backup file of this external file and point the existing link to it. Then you dont have to place it again, only aiming the link to the recovered file.
Also, site information usually have absolute coordinates and it would be easy placing it again.
Some security advices:
1- Lock this file, and protect it against erasing. Nobody unauthorized should modify it.
2- Make regular backups. In event of loss, you could recover valuable information. Follow the 3-2-1: 3 Backups, 2 in different media, 1 out of the office.
Regards.
Augusto Mora
Architect & teacher of Building Projects at CPIFP Pirámide. Huesca (Spain).
Revit 2014 certified profesional.