starttime=timestamp()
for i in objects where classof i == VRayProxy do i.filename=i.filename
thetime=timestamp()-starttime
print ("refreshed filename in " + thetime as string+"ms")
The stupidest of scripts, yet a blessing when there are changes to a proxy file that is present thousands of times in a scene.
This is the scenario that sparked the idea:
Empty scene, create a foliage, export to proxy with auto-proxy creation.
Now you’ll have one proxy displayed in view.
Create another, different type of foliage, and reexport with autoproxy (it will overwrite the old proxy mesh file).
Now you’ll have two proxies displaying different trees, but both are reading the same proxy file.
The script refreshes the proxy object filename for all the scene proxies, hence resetting the preview, and avoiding nasty accidents at rendertime 
Tested on an x2-4200 with a geforce 8800gts 640mb in d3d, 21825 proxies refreshed in 3 seconds or so.
Have fun with it.