award points to a user each time they update their cpt post

The save_post action fires when a post is updated and/or published, including when a new post is inserted. You can use it for custom post types also.

Assume that your CPT is book.

add_action( 'save_book', 'wpse63478_save' );
function wpse63478_save() {
        //Your Code to give point to user
}