Six years ago is almost exactly the same time that the ACA changed the route at the MT/ND border. So were you at the MT/ND border on the pre-2012 route, or the MT/ND border on the post-2012 route?
As John said, many people like to finish what they started. If you're one of them, then finishing the NT is probably a good idea. Your next decision is whether to take the full NT route, or to use the North Lakes Route and and possibly the Lake Erie Connector, because 1200 miles past the MT/ND border will get you to the point in MN where you have to choose. If you decide to take the North Lakes Route, you'll have to then decide whether to go through the Upper Peninsula or take the ferry across Lake Michigan. I went through the Upper Peninsula and took the Lake Erie Connector and I liked it.
You'll have to pick a place from which to get home at the end of the 1200 miles. I assume you'll want to fly home and therefore will be looking for an airport. Minneapolis, Chicago and Green Bay are possibilities.
You should then be able to finish the NT in your third segment in another year.
If you don't feel you need to complete what you started, there are of course many, many other route possibilities. Since you live in Vancouver, the Pacific Coast Route immediately comes to mind and is stunningly beautiful--more beautiful that what you'll see on the NT, and less lonely.
Have fun.