Replace them. NOt even a question. When you go to clean your own lines be sure to use an caustoc line cleaner. You don't want to just sanitize them, the point isn't sanitation, it's removing the build up in the line that changes the beer flavor.
If you have taps, maybe sure you completely disassemble them. If they have never been cleaned you will be amazed at how disgusting they are. Plastic picnic taps probably should be replaced.