Over time people develop tolerance (increased metabolism) to the benzos. It's a widely known occurrence with these drugs. Alcohol and other things also make you metabolize them faster.

In fact, it's almost guaranteed to happen in most people with regular dosing. Nothing to be concerned about.

I also have days where the anxiety is so profound that the klonopin doesn't even touch it. Just have to wait it out.

Talk to your doc about a klonopin holiday to let your system return back to baseline.