You might try the autosuggestion technique. For instance, when you’re lying in bed in the evening, repeat to yourself that you WILL become lucid this night and that your LDs WILL last longer than usual. Keep repeating it until you fall asleep, but the most important aspect is that you really believe what you’re saying. Don’t just ramble it, but put strength in your intention and almost will it to happen.
A more powerful technique might be self-hypnosis. It’s very similar to autosuggestion with the difference that during selfhypnosis you have to put yourself in a very relaxed state, almost in SP. Let your body and your mind become totally serene, yet without falling asleep. If any thoughts appear, don’t fight them actively but watch them passively from the perspective of a silent watcher. Once you’re sufficiently relaxed, say to yourself that you’ll count to 10, and when you get there, you’ll have total dream control (or full dream stability, or similar intentions). Repeat it a few times and then start counting very slowly. Make sure the counting is synchronised with your slow breathing, like “inhale/1…exhale/(repeat your intention)…inhale/2…etc…” The closer you get to 10, the stronger your intention and belief should be that whatever you repeat, WILL effectively happen. When you finally get to 10, make sure you’ll have the genuine feeling that your intentions ARE coming true, and that you’ve succeeded in your selfhypnosis practice. Then, say to yourself that you’ll slowly wake up from the deep relaxation/trance, but without losing all the intentions you’ve made, once you count back from 10 to 1. When you get to 1, slowly awake from the relaxation, move a few muscles and slowly get up. If you like, you can repeat this selfhypnosis a few time during the day. Also, do it every day because it may take a few days or so before you notice any changes.
Hope this might help 
Good luck!