@apples_and_pears You could go back in with a tapestry needle and weave in a new thread to match the pattern of the old. That would be easier on a simpler pattern though (like a standard tabby or twill). Because this is doubleweave, you are essentially weaving two fabrics that are interlaced with each other in this dense cloth, so it would be more challenging.

In my case I put on enough warp for three towels and I will probably not go to the trouble for this one.