Expired fire extinguishers can never be re-certified. Large fire extinguishers that last up to 20 years and can be re-inspected, but small fire extinguishers, such as those for cars, cannot be re-inspected.
You can bring the expired fire extinguishers to your local recycling park.
Finally, we would like to note that there is a difference between an expired fire extinguisher (usually older than 20 years) and an uncertified fire extinguisher.
As long as a fire extinguisher has not expired (this can be deduced from the production date on the device or the expiry date on the label, depending on the model), you can have the device re-inspected.