While upgrading your document from RapidWeaver 2 to RapidWeaver 7 isn’t impossible, it’s highly impractical.
As @MarkSealey mentioned, there is over a decade of code difference between the 2 versions. Much has changed, not only in RapidWeaver, but in the web as a whole.
I’d highly recommend taking this opportunity to reimagine your site and bring it up to date with current web standards. The biggest change would be making your site mobile friendly - RapidWeaver 7 helps you test / build your site around a mobile focus easily. The included responsive / mobile friendly themes are: Affero, Allegro, Kiki, Lander, Offroad, Reason, Split, Tesla and Voyager.
We have a bunch of free video tutorials on our community site to help you get acquainted with some of the new features and the interface in RapidWeaver 7: https://rapidweavercommunity.com/tutorials/free
And always feel free to give us a shout!