Naughty kitty. LOL We have a cat that eats knitting. She stays outside almost all the time, but we let her in a couple of times like when she was spayed and when she had to have her tail amputated. When she was in she ate holes in a sweater I knit a while back for my father and got back after he and my mother both died. Then she ate holes in a sweater I left in the car when the windows were down. It was not handmade, but I liked it.
Anyway..... Is it just plain stockinette stitch or something fancy? If it is stockinette you may be able to save some of it, if strands are intact and not weakened by chewing. You may be able to only rip it back a little to a point where things look pretty good and if there are stitches that are still dropped you can pick them up with a crochet hook and work them up.
If I were you I'd try to save some of it, you may succeed and if you don't you can always resort to a complete frog job. Not much wasted but a litlte time if you try and you will no doubt learn some things even if you don't succeed. And if you do....hurrah!!
If you haven't used a crochet hook to pick up stitches and "reknit" them, look up the videos about fixing mistakes. It is probably in the "Tips" section.