You probably have, at best, a 50/50 chance of rejuvenating such an old plant. In order to do so I would suggest preparing a new planting hole with a good amount of compost/really enriched soil.

I would clear the dirt off of the roots and then prune about 1/3 of the roots off. This will encourage new root growth. I would also prune the rose canes/branches by at least 1/3 to 1/2 with an emphasis on the removal of older growth that may not seem to be robust.  This will send a message to the plant to focus on new growth and not put its energy into trying to maintain the old. 

If and when new growth starts to appear, I would fertilize the rose to give it a boost. That could take a few weeks or even a month so patience is a virtue with this. You are doing a lot of shock treatment so it can take time for the plant to recover before it can thrive again.