Sounds like you may be losing focus. Focus on focusing. Look at stuff in depth so you train your mind to focus on what you want it to be focusing on.

I think you may have created a habit too. You start waking up during a LD too much and your mind thinks, "oh its a LD, time to wake up." Break the habit by not doing anything big.
I also noticed that the longer your lucids are the longer they tend to stay. It your is like 2 minutes than the next will probably be 2 minutes. Again, break the habit by not doing anything. If you chill your mind will chill out some too.