Press [Tab] just before entering the portal at the end of a level. After your ship disappears, leave and allow some time to pass. Return to the portal and press [Tab] to receive extra lives and time.
Easy points
Your score is limited only by your patience. This is because dumples bring 2,000 points apiece. On level 5, the game throws nothing but dumples at you. And before level 11, and in particular on level 5, you will get a free life every 15,000 points. If you can average seven and a half dumples killed per life-losing mistake, you will break even. If you can do better than that you can play level 5 indefinitely, gradually collecting more and more lives and points.