Not gonna lie, when I run into scenarios like this, I find out how much the polycarbonate lens'ed replacements are and buy them. they may be aftermarket, but poly is an absolutely fantastic material for this purpose.
That being said, you will either spend the time to go between grits like everyone else or spend the same amount of time jumping grits to get the material worn down to where the new scratches are at or below the old scratches. One is an investment of time more than money, one is an investment of money over time. Either way, 1400 grit was wayyyyy too low to stop for a clear finish. Even 2000 grit is. Personally, I'd go to a wet 4,000 grit and then maybe use a toothbrush and toothpaste on the lens after that since that stuff is incredibly light.
