I can suggest 2 things to do to maintain your dreams. I do it and sometimes it works:

-Meditate in the dream. When all starts to fade, put yourself into meditation position or just stand still. Breathe slowly, don't think about waking up, think of nothing and just watch. The environment might come back or even you might end up in another scenario.

-Use all of your senses. Curiously, this tip was given to me by a Dream Character. And it makes sense. When all starts to fade, quickly use your senses. Touch something, talk, focus on an object, smell, hear... This will keep you in the dream.