There was a judgement by the European court that the UK could unilaterally cancel article 50 and be back on the same terms but that is unlikely to happen.
Anyway I am not sure how the UK can get out of the current mess.
Possibly May could put the deal to a referendum, though this opens up a can of worms, what would the question be, would a rejection mean renegotiation, no deal or staying in the EU.
A general election most likely leave us just where we are today with small changes in numbers, the problem with the first past the post system means that political parties MPs are a mish mash of different viewpoints
I am not sure May can reach over to a cross house support for some kind of Brexit because of the baggage she has, could another Tory leader do this, I can't think of anyone and Corbyn i charge of Labour makes it much more difficult anyway
Perhaps if those who Labour MPs who don't like Corbyn formed a new party, (they can't change the leadership), then there may be a way forward, but I can't see this don't underestimate the psychological attachment to the Labour brand.
So we may be stuck with No deal brexit.