Send yourself on a trip to a distant country. One involving some form of tour/trek in which you are not in control of the schedule. The combination of being forced awake to meet itinerary deadlines, plus seeing and interacting with a different culture or cultures, possibly sleeping in a new bed each night, should help "shake loose" the rut you're in.
When you return, give some serious consideration to similar "coached" wake-ups in some other way – agreeing to carpool with folks who go to work earlier than you, joining a gym bootcamp, dating someone who is only free during the mornings, etc. Sometimes, you simply have to incentivize a new process until it has time to become the default/habitual response.
Simpler/cheaper things to try around the house: a rotation of alarm clocks, sleeping in different beds/couches/orientations each night, going to the gym right after dinner and really wearing yourself out, then going to bed immediately after getting home, no snacks/dessert/etc…
You may also want to look into sleep disorders with your doctor, or with Cognitive Behavior Therapy (CBT) methods, which help you more easily set a course, and track progress in ways that don't create "catastrophic failure backsliding" (CFB, aka Deano's Disease).