If you're just a row away from the missing row, you could try tinking
back that single row. It's a bit tedious for so many sts but do-able. That said, I think your suggestion to add an extra row in now will work too. The dark yarn will work in your favor because it'll hide these kind of mistakes. (Of course, reinseting the needle into a knit row is ideal, as GG suggests.)
Your afghan so far looks lovely, btw. Beautiful work.