Maybe you just need a change of some sort, a spark.
The mind plays a massive role when it comes to lifting, do you have like minded lifters around you in the gym, or sissy boys wearing lycra and curling in power racks.
Dont dismiss all these things, you may think I'm being funny, but if you walk into a gym and some guy is squatting 4 plates and another is deadlifting 5 plates, surely thats going to inspire you to lift.
Is the gym you train at somewhere you WANT to go or HAVE to go?