Modifying a Proxy rig.

I have two blend files, fancycar.blend, and shot2.blend.
I created the rig and mesh in fancycar.blend. After I group the rig and mesh, I make a link to the group in shot2.blend. I the rig a proxy object, and start to animate. Later, I come accross a problem that will require a change to the rig. I modify fancycar.blend, but the rig does not update like the mesh does. Is there any way to fix this?