"For the First Time in Forever" is a song from Disney's 2013 animated feature film Frozen, with music and lyrics composed by Kristen Anderson-Lopez and Robert Lopez. It is reprised later in the musical. Both versions are sung by sisters Princess Anna (Kristen Bell) and Queen Elsa (Idina Menzel).

The song was composed relatively late in the production process in June 2013. This was only five months before the film's November 27, 2013 release date, when the filmmakers were scrambling to make the film work after realizing in February it still wasn't working.

The original version of the song contained a line about "I hope that I don't vomit in his face," which was deemed unacceptable by Disney as a reference to bodily fluids. The Lopezes' daughter, Katie, came up with the replacement line that ended up in the film: "I wanna stuff some chocolate in my face."

As for the reprise, there was originally a different confrontation lyric for the scene where Elsa strikes Anna with her powers entitled "Life's Too Short" (the premise being that life is too short to waste it with someone who doesn't understand them), which itself would have been reprised later when the sisters realize that life's too short to live life alone. As the characters evolved throughout the writing process (specifically Elsa was turned from a villain to a tragic hero), the song was deemed too vindictive and was instead replaced with a reprise of this song, to create a motif. "Life's Too Short" survives as a demo track on the Deluxe Edition of the movie soundtrack, and part of the melody was reused in Frozen Fever for the song "Making Today A Perfect Day".

When the necessity of a reprise dawned upon Anderson-Lopez, she wrote it in only about 20 minutes, and then successfully pitched it on her own to the Disney production team, as Lopez was already with the team in Los Angeles trying to fix "Do You Want to Build a Snowman?"

...
Wikipedia