You can get beer line from the homebrew shop. You can buy a splicer if you want and just add it on the end, or you can have one continuous piece, it's really up to you.
If you decide to replace the whole line it's pretty easy. I'm guessing the tower has a short elbow shank, so all you need to do is pop the top off the tower, unscrew the nut on the back, and slide the shank out the front. Then you remove the old line and install the new one. It's really not that bad, I did four of them a couple of weeks ago.