You can use the custom JumpStart installation method to upgrade. In the custom JumpStart profile, specify install_type upgrade.
You must test the custom JumpStart profile against the system's disk configuration and currently installed software before you upgrade. Use the pfinstall -D command on the system that you are upgrading to test the profile. You cannot test an upgrade profile by using a disk configuration file. For more information about testing the upgrade option, refer to Testing a Profile.
You can use JumpStart to update a clone system with a Solaris Flash differential archive. For an overview of Solaris Flash archives, see Chapter 17, Solaris Flash (Overview and Planning).