There’s a huge problem with your process if it takes you hours to rebuild it. It shouldn’t even take 15 minutes to set up the new version like you had your old one.
So you print it on paper? I just import the screenshot of the previous version into SketchUp as an image and use it as a reference.
Use the Extension Warehouse and the Sketchucation Extension Store tools to automatically install current versions of the extensions you have in the previous version. They can both install them en masse.
I usually take the time to do some house cleaning, too, and get rid of or disable extensions I haven’t been using so I don’t have to wait for them to load at start up.
Here’s a little more: Migrating to SketchUp 2017