When you start a level, choose Renfield. Play through the level and try to keep one of the green pegs on the screen. If the last orange peg is near, aim for one of them and fire. If done correctly, you will have a Spookyball on your Fever. When it lands in any of the holes, it will pop up again at the top, giving you the chance to possibly get 200,000 points with one Fever.