I want to quote a line from a film in my novel. Specifically:
"Don't ever lose your sense of humour, Dan. Don't ever lose your sense of humour."
From About Last Night (1986). So, it's not a long excerpt, just two sentences.
I know I can't quote a single line from a song without incurring expensive permission fees. But, that's a short body of work. Does it apply to movies, too?
No. This is fair use under U.S. Copyright law, which allows you to use portions of a Copyrighted piece as long as you are able to demonstrate that you are using the quote in a transformative manor (presumably a character is a fan of the movie and is quoting it because it institutionally appropriate). Consider Arnold Schwarzenegger's catchphrase "I'll be Back" which is worked into almost every movie he's done. The original line was written by James Cameron for the 1984 Terminator Film. At the time of writing, Arnold didn't really think much of the line. Cameron said he thought that the line would be funny only upon repeated viewings and was surprised that it first time audiences laughed at it, having already anticipated the titular character's penchant for machine like understatements.
Since then, the use of the phrase was used in Every Terminator Movie (including one where Arnold was not available for filming due to being governor of California during filming... it was said by John Connor (Christian Bale)) and most, if not all movies Arnold has a significant role in, as a sort of in joke for the audience with little suit from James Cameron or the Franchise owners. In addition, no Arnold Parody is complete without some use of the line, and almost everyone has an "Arnold" parody.
Fair Use is an affirmative defense, meaning you must say you're going to use it as a defense (and then prove why it falls under Fair Use) rather than assume courts will enforce it for you.
