Meeting in the northeastern city of Lille, the 49-year-old was expected to unveil the party's new identity, burying the National Front (FN) name that has been associated with her father Jean-Marie since 1972.
The switch is meant to signal a new beginning for the anti-immigration movement - and a decisive break from the toxic past of Jean-Marie who was finally banished from the party.
Le Pen scored a lower-than-expected 34 percent as she lost to President Emmanuel Macron last May and has since struggled to assert her authority after admitting to mistakes during her campaign.
"Without a name change, we will not be able to forge alliances. And without alliances we will never be able to take power," she said as she faced questions from many skeptical members.
She will address the party faithful later after being re-elected as leader with 100 percent of votes on Sunday morning after standing unopposed but has kept the new name a closely guarded secret.
The party is expected to keep the word "national" in its new name. "Rassemblement national" (national union) has been mooted as an option.
Le Pen won a major boost on Saturday from former Donald Trump aide Steve Bannon who appeared alongside her at the National Front conference and told delegates that "history is on our side."
Bannon's appearance reinforced the links between the Trump campaign and France's far-right party which hold similar views on immigration, Islam, trade, the EU and Russia.
The presence of the former head of Breitbart News drew a stinging response from Macron's government.
"The king of fake news and of white supremacists at an FN summit... why am I not surprised?" remarked parliamentary affairs minister Christophe Castaner, who is also the head of Macron's centrist Republic on the Move party.
"Change of name but not of the political line."