When I changed bars I kept my brake line, just tied it to speedo cable about halfway down with a couple of small, black zip ties to neaten it up. Changing the line is a simple job, but if you've never worked on brakes before, you may have trouble bleeding it. Of course, brakes aren't something you want to take chances with.
The only thing I changed was the clutch cable. The extra length caused a little binding when I worked the clutch. I used a Speedmaster cable.