I think of dreams as a way our unconscious mind sends a message to the conscious. When I can't remember a dream, and I want to, I reassure myself by thinking that if the unconscious is trying to send me a message and the message is an important one, the unconscious will try again. I have had the same dream in several different forms that repeated until I "got the message." So I guess just be patient, and the message will be sent again.

That said, when I really wanted to remember a dream, I tried to lie still in bed, with eyes closed and visualize my brain as having 2 entrances. I would let conscious thought (being awake) drift out one of the entrances and that made it possible for the unconscious dream to flow back in the other entrance. I found that once it started flowing in, I didn't even have to wait for the whole thing. I could just grab it by the tail and remember it once I had a bit of the dream I had already dreamt. This was a visualization that worked for me. Probably sounds bizarre to others. You will have to come up with what works for you.

Good luck.