Mr.Padawan,
Renewing the certificates is possible in AX.
I guess you have valid certificate for now. Make sure certificate is installed in IIS Server in which Async Server is running. If you go to details, you will get the thumbprint of certificate - which is required for updating in Async.
Open C:\Program Files (x86)\Microsoft Dynamics AX\60\CDX\Async Server\Package in your Async Server Machine and locate web.config file.
Open the config file in notepad and search for "thumb" and you will find lines like below:-
<behaviors>
<serviceBehaviors>
<behavior>
<serviceMetadata httpGetEnabled="false" httpsGetEnabled="false" />
<serviceDebug includeExceptionDetailInFaults="false" />
<serviceCredentials>
<serviceCertificate findValue="xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" storeLocation="LocalMachine" storeName="My" x509FindType="FindByThumbprint" />
<userNameAuthentication userNamePasswordValidationMode="Custom" customUserNamePasswordValidatorType="Microsoft.Dynamics.Retail.SynchService.ServiceLibrary.Authentication, Microsoft.Dynamics.Retail.SynchService.ServiceLibrary" />
</serviceCredentials>
</behavior>
</serviceBehaviors>
</behaviors>
Replace the xxx part with your new thumbprint. Clear SSL cache and restart the Async Server.
You are ready to go ahead.