Start an "experiment" where you don't take them at all or you don't take them until Midnight (if you are not asleep yet), get into a different pattern.

I use my allergy meds to help me sleep sometimes but I mess with the vitamins and meds I take, trying out different times and combinations of when I take them, etc. That way I don't take any particular pill so I get habituated to it. I have arthritis and take pain pills but I take different things to help, sometimes I use the allergy to make the sleeping more likely (so even if I'm in pain I can't wake enough that it matters :-) sometimes I take Advil before I go to sleep, sometimes I wait until I wake and hurt, sometimes I take before and if/when I wake and hurt, etc.

Play games with yourself. Start a serious list of okay things during the day and bad things and make it so enough of the okay things grant you the sleeping pill at X o'clock, otherwise you have to stay up 2 more hours doing okay things like reading, taking a soothing bath, watching TV or playing games on the Internet, etc., whatever you enjoy most. Eventually there will be okay things and you won't necessarily want the sleeping pill/day to end. Make it like the opposite of coffee :-) I get up sometimes to get to my coffee. Make it so you don't want to "have" to take the sleeping pill.