The latest version of Ovation Pro can be downloaded from the Ovation Pro site. This is currently version 2.77, and is available from http://www.davidpilling.com/ovationpro/opr.html.
In order to make use of this upgrade, you must be running a version of OvationPro that is at least 2.60. If you are still on a version earlier than 2.60, then you are strongly recommended to upgrade to 2.60. It is well worth it.
If you are seeking to upgrade the applets provided with the Ovation Pro application, then you must visit the official Ovation Pro site maintained by David Pilling. There is now a complete set of Applets available there.
An upgrade is not much use if you do not any version of Ovation Pro to which to apply the upgrade. If you wish to sample the delights of Ovation Pro, then a demonstration version can be downloaded from the Ovation Pro site.