I think you are just getting used to becoming lucid in a dream and the initial excitement you always got is gone now, this both a blessing and a curse cuz on the one side you won't wake up because of over excitedness but on the other LD'ing seems to have lost its "lustre", I say this because a similar thing happened to me because when i became lucid i would never have much control. Learn to stabilize and also make some goals to keep you motivated..