There is no way to really get it nice once the fog appears. You have 2 options: 1. Ask an upholstery place to take out the old plastic window and sew in a new one. I had this done once and had great results. I don't believe there will be a warranty on their work though because who can guarantee something like that.
2. Get a new top. That is what I did with my current car. You should replace your top every 12-15 years anyway. I replaced mine at around 17 years because it had shrunk even though my window was in good shape. It's better for the top frame and you can do repairs like replacing the tension wires while you are in there. Plus, it just looks nicer. Get a nice one though. I recommend purchasing your top online and getting as good of one as you can afford like German Sonneland Canvas then asking a shop to install it since most places will rape you on the cost and sell you the cheapest top they can get their hands on. The installation cost is almost always around $350-$400
