I have recently moved into a home that has a very neglected back yard. This summer, I found a grape vine that looked as old a Methuselah that had been cut down. By some sort of miracle, it produced some leaves, and one lovely cluster of green grapes. (Photos attached) How do I rejuvenate this vine again? The grapes were not seedless, but still delicious. Is it worth saving? Should I pull it up and plant a new vine? How do I go about trimming such a thing?