Mix it with some moisturizer.
um....well....throw it out and buy a new one! easy as that! they arent that expensive!
i mix 2 concealers to get a match for my skin because i have yet to find one that does perfectly!
White eye shadow is good, just don't put shimmery white eye shadow.
Put foundation or concealer in it. :)
I don't know what kind of packaging that has, but if you could you could add lighter foundations of crushed up powder to it. Another thing you could do is apply it as normal and then use a light colored setting powder. Maybe you could even get a light-reflection powder to make the light reflect more.
Hope this helps!