I think perhaps you're having what they call a recall slump. It's basically this annoying thing that happens to you where (sometimes explain-ably, sometimes not) you cannot recall dreams as well as before. Follow the advice in the other posts for how to better handle one, or just wait for the slump to blow over.

But if you want to boost enthusiasm for Lucid dreaming, I recommend making a list of exciting things that you want to do in dreams. Just stop and think of all the amazing things you can do and places you can go in a dream. Or you can read though others dream journals on the site. After some digging, you should come across one that you enjoy reading and can inspire you to want to have the same sort of experiences.