You can no longer update to the 3.5 version of DVD MovieFactory because it is too old and the developer doesn't provide it anymore. In the meantime, Ulead DVD MovieFactory has been rebranded into Corel DVD MovieFactory and the current version is 7. The new product can be found on Corel's official website.
As far as updating your edition of Ulead DVD MovieFactory goes, according to the page previously mentioned, you can do that, but you're going to have to pay for the update. In case you need additional details, I recommend contacting Corel directly using this link: http://www.corel.com/en/contact-us/