As I said previously........if we do have a second referendum there should be no third option. We leave with the deal negotiated by the PM or we leave with no deal.
As you have rightly said, we have already decided to leave. Remaining should not become the third option.
If there is a second referendum I expect the question will be heavily loaded against leaving and I doubt No Deal would be presented as an option, unless it is used as a three way question to split the leave vote. Leave with no deal, leave with May's crappy deal or remain.
But I think it will be something like, May's crappy deal or remain.
Sadly I suspect Remain would win such a vote, not because Leavers have changed their minds as is claimed, far from it, but because people would be so disillusioned by this governments incompetence that the leave turnout would be low and remainers would be more motivated.