The cult comedy aired on Starz for two seasons between 2009 and 2010, with a movie having been rumoured since the show's axe.
"We're hoping that the Party Down movie happens," Caplan - who played Casey - told the Comedy Bang Bang podcast. "I don't see why it wouldn't but... nothing is set in stone."
Party Down also starred Jane Lynch (Glee), Adam Scott (Parks and Recreation) and Megan Mullally (Will & Grace).
Though the series struggled with low viewing figures, it was popular with critics and was nominated in the 2010 Television Critics Association Awards.
Series co-creator John Enbom is believed to be working on a script for the movie adaptation.
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Watch a clip from Party Down below: