Is there an easier way to change the keysize of digital certificate without generating a new digital certificate and sending it out to be signed?
There is no quick method of changing the keysize of a digital certificate.
A new certificate has to be generated to change the keysize of a digital certificate.
It is when you generate the new certificate with a TSS GENCERT command that you specify the new KEYSIZE. It is the only place where you can set the KEYSIZE of a certificate.