Carrie Fisher's death last year was a major blow to the many fans who took inspiration from her life, as well as her work as a writer and actor. She'd completed filming for her final turn as General Leia Organa in Star Wars: The Last Jedi before she passed, but sometimes, filmmaking demands that actors return to the recording booth. A new quote from director Rian Johnson talks about how he dealt with this problem.
The process of putting newly recorded dialogue into already filmed scenes is called Automated Dialogue Replacement (ADR). Usually, it's as simple as getting someone back in front of a mic and getting new line readings, and it's a regular occurrence on most productions. But in a case like this - where a performer has died - it's a lot trickier and far more poignant. You get a sense of that in remarks Johnson made to Rolling Stone:
"We had to do a lot of sound work and that was kind of tough, but we managed. We have a great sound team and we managed to pull her dialogue out and find little snippets from here and there and make it work. You do what you've gotta do."
There was some confusion as to whether we see a digitally recreated version of Fisher as Leia but the last word from Lucasfilm was that it won't be happening. Good thing, too; it'd probably be a heart-wrenching experience.