I have been using this trick for over a year now, it's giving me great result so I decided to share it with you guys.

I always have scratches on my layerlens GoPro Lens Protector, and it's making my footage look blurry. Even after replacing the protector, it gets scratched very soon because I crash a lot.

   

So I bought some Tablet Screen protector (or iPad screen cover), and just cut out a little piece and stick it on the lens.

   

It works like a charm, and if it doesn't damage the lens anymore just the cover, which you can replace easily and cheaply. With each screen protect it costs only $2 and I can cut it up to 12 to 15 pieces !!!

I use a little marker to draw the outline of the piece I need to cut.

   

   

Make sure there is no dust on the lens before you put it on. use a credit card to push out any bubbles.

   

In fact you can use it to protect any flat surface, for example your Taranis Screen!!!  

Excellent tip!!
I guess you need to get the sticky type of protector otherwise it might fall off your lens after impact...