Do you have a sewing machine? Can you sew? Ours remain in good condition. It looks to me to be an easy replacement. Just some small nylon twine to replace what is there. A stitch ripper to open up the old slot, remove the old twine and sew in the new loop. I suspect that Joann Fabrics would have what you need along with the small clamp that ties the loop together. Rather than the clamp, stitch the loop together. Easy, peasy, Japaneasy.
In the absence of a sewing machine, you can hand stitch the new loop to the shade, which is what I would do. Our boat has two sewing awls that come in handy for those fabric repairs.