No, unfortunately no refunds are issued once the e-vignette has been activated in the Czech toll system.
The vignette will be active until the end of the purchased validity.
Related articles:
Can I cancel my digital purchase of the Czech e-vignette?
Do I get a refund for the Czech e-vignette if my car got stolen?
Do I receive a refund, if I take my vehicle off the Czech roads and return the number plates?