Yes, you need more of the lemonade. That's your only source of nutrition on the fast. You can add extra maple syrup if you need to. Since you are on your feet all day and constantly in motion, you should drink all 12 glasses - and possibly more if you still feel this way.
I would suggest that you look into juice fasting if you increase the amount of lemonade you are drinking and you *still* have these side effects. You may be detoxing too quickly.
Blacking out or feeling dizzy is not cool, no matter what kind of diet you're on. Take care of yourself, don't sacrifice your health even when you're trying to be healthy. Okay? :)