Because the ERG ("European Research Group", including MPs like Jacob Rees-Mogg) pushed a UK ammendment to include the March 29th leaving date into UK law, MPs will need to revoke that to make it possible to retract Article 50. It is unclear whether the current pariament breakdown would support removing that ammendment.

The key question is how blocking a no deal Brexit will be implemented, given the rejection of the withdrawal agreement (not a deal!) and the reluctance of the EU to extend the Article 50 period without something different such as a general election or people's vote. There is also the upcoming European Parliament elections in 3 months which -- if the UK stays past that point -- the UK would need to participate in if Article 50 was extended past that point.

A general election is also problematic as it will likely result in another hung parlaiment or slim majority and we will be back where we are. This is especially the case given that Scotland is overwhelmingly SNP, and may gain seats over the Conservatives/Tories.

While a people's vote may be a potential way out of the deadlock, the government (and maybe the majority of parliament) are against it. Even if there is a majority for it, there isn't a majority for what to ask in the new vote. There are MPs that don't want remain on the vote, and there are others that don't want no deal on the vote.