Yes, you will. Without a method of cooling the lines, they will eventually warm up. There are three basic ways to cool your lines: liquid, air, or conduction.
Conduction is the easiest. I have seen here where many people have basically put their lines into a copper pipe and make sure the pipe sticks into their keezer so that the coolness is conducted through the copper tube.
Air cooled is the next easiest. Basically make sure your tubes that your lines are in are wide enough to allow air to flow through. Then add some computer fans to blow the cold air from your keezer into your line tubes.
Liquid cooled is the most difficulty. You use either water or glycol, depending upon the temp of the liquid you'll be running, and then you pump it through tubing next to your lines to keep them cool.