Bake 40 to 45 min. or until centre is almost set. Run knife around rim of pan to loosen cake; cool 1 hour before removing rim. Refrigerate 4 hours. Meanwhile, bring cherries, water, tapioca and remaining sugar to boil in large saucepan, stirring constantly; simmer on medium-low heat 2 min. or until thickened, stirring constantly. Refrigerate until ready to use.