How does my anxiety medication work?

About two weeks ago I started taking Buspar, currently I am taking 7.5mg in the morning and 15mg at night but soon I will start 15mg 2x/day. I finally built a tolerance to it so it no longer makes me tired or gives me that chill feeling, will it still work for anxiety? I don't really know how Buspar works, I guess at the beginning I thought it was that chill feeling that helped with my anxiety but now I don't get the chill feeling. I guess I just want to know if Buspar still helps anxiety if you don't get drowsy or chill after taking it?