I'd tell you to get to tea. I've been drinking around 1 - 2 liters of coffee a day for around 5 years, and when i switched to tea in order to stop the caffeine from f*cking up my sleep cycle, i had around a week of headaches and a slight loss of energy, but after two weeks it went back to normal. I kept on drinking tea for around 2 months after, and now caffeine gives me that tremendous rush again, so i guess i'm fixed ! Also, i'm rather young (22) so this might have speeded up my recovery, but i think you should give it a try !