Just call me cheap........................but, I would put a dab of aqua seal on the slice and fish away. I would do this until I actually noticed a real problem not an imagined one with the line. My ulterior motive for doing this would be to drive my buddy up the wall while I continued to catch fish with line that definitely will not cast or float.
In closing Rich, you say you fish wet flies and streamers with it. I would not replace the line, I would probably dye the tip for about ten feet to a nice camo tone and fish away.