I doubt they are dulling and losing colour, yes as you get a great deal older your eye colour can shift somewhat but it is probably just a change in light that is making you believe that they are fading.
No eye spell will work, you cannot make them glow or change colour etc, what you have, you are stuck with.
Sterben, 3 different people said it doesn't work, one person with a blank profile said yes, please don't listen to the random stranger. you can try the spell for yourself but magick does not create dramatic physical change. this is why we said no, but provided this doesn't require money, personal information, or any physical harm, give it a try and see for yourself.