Your just developing a tolerance. My first couple of months of smoking were magical and amazing, and after that it becomes a little more normal, and you are no longer surprised at your high. I suggest you take a break, maybe 2 weeks or more, and I bet you can recreate that feeling.

the hardest thing though is gonna be stopping after it's become a part of your daily routine, so you might wanna find something else that will occupy your time and attention instead of weed.