I was replacing a rather broken piece of glass on my macbook pro 13" and got impatient toward the end, managing to slip and scratch the LCD screen itself. Before I cover it up with the new piece of glass, I'd like to try to at least reduce the visibility of that scratch, if not repair it. Is there anything that will work on the LCD screen itself (all the tips I've come across are for the glass)?
You have no good options for repair.
Any mechanical stress you add could sabotage the panel later making it more likely to crack. Any coating you try has worse side effects as it ages.
I would make a judgement call based on the location of the scratch, the depth of the scratch and your temperament. If you can live with it, just continue with the repair.
If you know it will drive you nuts or is on a part of the screen you look at often, bite the bullet and buy a new LCD panel. Sell the scratched one to someone that isn't as picky (you probably know several people that use a phone with broken glass for months and maybe someone that even uses one with chunks of the digitizer missing). You could probably charge someone your costs for the panel to repair their Mac and come out of it even.
Now i don't think you can fix that, but here's what you can do : Go to a computer repair shop and tell them what happened. They will maybe order you a LCD Screen or there's one option. Buy a new LCD Screen at BestBuy, they will give you a new one to you around $110.99