At this point, it's impossible. Otherwise, then there would never be any reason for you to upgrade to a new version, and we'd go out of business. That's bad for us AND bad for you.
If you don't want to purchase a renewal, you can still keep using the program. It will never expire, but you won't be able to use the latest version (to be released in July 2011).
Regards,
Yuri Rai from Heaventools Software