It's best to just keep relaxing into the SP. If a dream doesn't seem to be forming, help the process by visualizing exactly where you want to be in the dream - a beach or a club, for example. Hear the noises and imagine the feeling of the ground under your feet; visualizing can trick your mind into thinking you're already in a dream so it'll complete the picture for you automatically. Don't forget to keep reminding yourself that you're dreaming, though!

If that doesn't work and the sleep paralysis seems to have gotten quieter or isn't there anymore, you can always try imagining yourself rolling out of your physical body. Don't try to physically move (you might still be awake), but imagine the sensation of rolling out of the bed, how the blankets on top of you will move, etc.