I have created approx 2000 drawings and set all xrefs with a relative path.
I then copied the entire job onto an external hard drive and this was the copied to a server elsewhere.
The xrefs cannot be found. Is there an easy way, without opening up all drawings and repathing to find the xrefs?
 
I could understand if I had this problem with a full path, but these were all set up using relative.

Try using "Reference Manager", an AutoCAD utility you should have in your AutoCAD folder.