Athena Chu, like Chow, acts in two previous installments.
They will be replaced by younger counterparts from the mainland. Han Geng, 32, will play Monkey King as well as Joker, the monkey's reincarnation, and actress Tang Yan, 33, will continue the emotional entanglement with Joker playing the Fairy Zixia.
Actress Karen Mok is the only one from the old cast.
"I felt like I was returning home the moment I began work on the new film," a nostalgic Lau says.
"All the memories came flooding back."
Lau says the latest will provide answers for some of the unsolved puzzles from the first two episodes.
He says it took a lot of persuasion to get both Han and Tang to join the cast of the film. He waited for eight months for Han to agree.
Revealing why he took his time, Han says: "I was reluctant because I felt huge pressure.
"It will be really difficult to improve on a role that has been perfectly played by Chow before. Inevitably, I will face comparisons, but none can finally refuse to play their childhood idol?"
