In my experience no, if you're newer to meds (within last few months) then one of the bigger mistakes is to keep upping your dose until you get the feeling again. I think you'll never work quite as well as the first time on meds but you'll notice it still does make a difference. I went through the exact same thing and increased my dose a few times before decreasing it (because the side effects started getting to me) and I ended up realizing it worked for me without feeling anything. The results showed in my performance in classes, higher GPA etc, I never felt the extremely motivated feeling I had first while on meds again but you get used to not having that.