How do I keep my dream going?

I've had two lucids where I'll perform a reality check and know it's a dream. I wake up feeling my physical body sleeping. I tried in my second dream to rub my hands together because I heard that helps to stimulate your dream senses, but I still drifted off and woke up:/

Have you tried Dream Spinning? The feeling of spinning around should stabilize you. Also yes, like you said it helps to stimulate your dream senses. When you have a sensation, you're not actually feeling anything, it's just your brain simulating the sensation. So if you do something for all of your senses (Smell something, look closely at your hands, taste something), it really makes the brain focus in on the dream by creating those sensations.

Try combining several senses, like hearing and seeing. Both of these sensations will give you a better clarity of your environment, rather than your body.

For example, try yelling out at people and seeing if they notice. This can trigger dialogue with your DCs and would further ground the dream.