Actress Christina Moore took over the role of Laurie Forman from Lisa Robin Kelly during season 6, but many fans still wonder why the original Laurie left That ’70s Show. The That ’70s Show Laurie character was the older sister of Eric (Topher Grace) and the daughter of Red (Kurtwood Smith) and Kitty (Debra Jo Rupp). Laurie came off as extremely manipulative, and her parents didn’t have the highest expectations of their daughter, but it was clear she was Red’s favorite. Kelso (Ashton Kutcher) was one of Laurie’s many secret flings, despite Kelso dating Jackie (Mila Kunis).
https://screenrant.com/that-70s-show-laurie-forman-recast-reason/