Sreeram,
Its slightly complex Solution ..... first of all you need to find the old documentation .. how this has been implemented in the past ...
Basically companies Security or messaging team generate these Certificates .... and they will provide you keystore file which you need to replaced ... Clarity Home Directory \ config Folder...
Few more steps to find out the Name of Certificate already deployed.
Open browser and login to clarity :
On the browser there is symbol as Lock (pad lock Icon).
Click Icon and view the certificate.
You will see the Certificate as Name of Clarity ..... You need new certificate as denclarity .
You need to involve you security team to proceed further and read the guide suggested by Dave
-Gurjeet