Question: Why didn't Alex Vincent reprise his role as Andy?
Bishop73
22nd Mar 2018
Child's Play 3 (1991)
Answer: To add to the other answer, the writers and producers felt that after two movies they had gone as far with child Andy as they possibly could have. They felt it would be too redundant to have a third film with Andy as a kid being pursued by Chucky. So they set this film years later when Andy was a teenager.
Answer: The film makers wanted to make Andy older in the film so he could have a love interest and be in military school. At the time Alex was only 9, but they wanted Andy to be 16. So they recast the part.
Bishop73