Just run it 'till it breaks. Of course if you think it may bite you than shoot it :<0) It looks like a pretty straight crack and I would guess it will keep going that way. No telling though, it may take the less route of resistance and head back at the toe. I had a hollow ground that had a crack like that and I thought i got the crack out grinding. It came back with a vengeance right down the path of the edge.