Welcome back to the Centrify Express forums.
Moderation note: always provide the operating system name and version when posting.
Since we don't know your OS, you can unzip the Centrify tarball and run install.sh; it will identify the older version and provide you the option to upgrade in place.
Alternatively, if you can use the native installer as well. For example, if you're using RHEL you can use RPM or Yum.
E.g. rpm -Uvh centrifydc-version.rpm or yum update centrifydc-version.rpm
R.P