i use a teeny steel crochet hook. i have one that is needle fine (i love garage sales!) and i put it through from the wrong side of the fabric-snag the "snag" with the hook, and ease it back through. then i work the edges with my fingernail to blend the visible pull in the fabric. you have to be careful, but with a little counter pull, and a soft touch, you can often blend it or "feather" it so it's not as noticeable.
good luck!