A good upholstery shop can make a new panel for you. I don't think you can restitch and do a proper repair. I had the same thing on the front seat of my Swinger. My upholstery guy said he could have made a panel to replace the torn stitching but I had already bought a Legendary cover so he installed it for me. The original cover lasted 50 years. The replacement will last as long as I live and probably the next few owners.
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