Here's a speculation. By basically not talking about it, she hopes it will be adopted by default.
If ERG can't agree and don't publish their plan, we face a choice between chequers and no deal 1/
A second referendum would spell havoc for her plan, create deep rifts in her party. Especially given how big the lead for Remain is now, it's not in the government's interest to have a #PeoplesVote /ends