Why is klonopin (clonazepam) not showing in my urine if I am taking it 3 times a day?

Metabolism. If it is certain that you are taking Klonopin (clonazepam) and it is not showing in your tests , you may be rapidly metabolizing the medication. Talk to your doctor to investigate this option.
It should. Perhaps the assay was not specifically looking for Klonopin (generic, clonazepam), a specific benzodiazepine. An assay will only find what it is looking for. It won't be found if, for example, the test was searching for cannabis and opioids, and not looking for benzodiazepines.