No, she need to keep spending democrat election funds right up to the election. Wouldn't want that money to go to a more competitive race.
Don't give them any freakin' ideas, people!! In 2008, when sitting Sen Toricelli was polling behind the Republican challenger in NJ (due to a - get this- "ethics controversy"), he dropped out. Unfortunately for the Dems, it was after the explicit deadline for another candidate to be added to the ballot. The Dems aded Frank Lautenberg anyway. Unfortunately for the Rule of Law, the NJ Supreme Court went along with it. Lautenberg won.
Same thing happened in 2000 in Missouri, when sitting Gov Carnahan died (plane crash) just before the election. His wife was allowed to take his place, despite election law. She won.
There is no shortage of recent election recounts where the recounts did not finish until the Dem was ahead, and then the counts stopped immediately. Washington, Ohio, Florida, Minnesota, etc.
Never, NEVER forget that they do not have to follow the Rules!! The power-hungry do NOT give up power willingly... and the Hard Left is in charge, and hungrier than anyone we've ever seen in this country.