Meanwhile, drain raspberries, reserving juice in medium bowl. Spoon berries into fine-mesh strainer; place over bowl of reserved raspberry juice. Press berries with back of spoon to remove as much juice as possible. Discard strained solids. Mix jam and remaining corn starch in medium microwaveable bowl until blended. Gradually whisk in raspberry juice until blended. Microwave on HIGH 1 to 2 min. or until thickened, stirring after each minute. Refrigerate until ready to use.