Just keep going if you don't want to use chemicals; keep digging it out every chance you get, and in the end it does disappear. I've had acres of couch, bindweed, nettles and ground elder, and thopusands of weeds coming up everywhere I dug. It's only the ground elder which is still a problem, and even that's diminishing. It just needs time, but I know, it is frustrating when the weeds keep coming back and smothering your veg!