in the cr2 for the robe, replace all instances (there should be 2) of the old obj with the new object and then save the cr2 under a new name as well. if you have changed the materials, you need to edit these in the cr2 as well. then bring the robe in from the library using your new cr2 instead of importing the new object. If you havent edited the object in any way except for materials, it should work fine.