How To Upgrade Hana Dev Edition using CAL?

Hi,

I already have the SAP HANA Rev 72 installed in my AWS instance (instance type m2.4xlarge). It was installed using CAL. How do I upgrade to SAP HANA Rev 80 or to newer versions by using CAL and by using the same AWS instance (if the requirement is the same instance size)? I don't want to lose what I have already created (views, etc.) in previous SAP HANA versions.

Thanks for your help.