You have to renew your certificate before the date of expiration.
If you failed to renew your certificate on time, you can't take our refresher.
Failing to renew your certificate on time means that you have to start over again completely. This means you start again with the A1-A3 training (passing the A1-A3 exam), before you can proceed to the A2 training (passing the A2 exam).
The refresher course exam is only valid if your current certificate is still valid.
Of course, we will help you further if your certificate has expired. Please contact us.