How do i keep my hair color from fading?

my hair naturally dark brown almost black hair was a blondish color by using Loreals color for dark hair sold at sally's beauty supply. Well i kept dyeing it that color for about a yr. Now i decided to go dark again and i used loreal's mega brown color in truffle and naturally dark colors fade the firs couple of washes. but my problem is it is fading way more in the parts where my hair was blonde and where my roots were dark its not a problem. So what should I do to prevent the other parts from getting light again. I know i'm not going to have a choice but go back and dye my hair again especially where i had the blonde color. HELP PLEASE%26gt;

thanks

How do i keep my hair color from fading?

unless you have magical powers, you can't! the only way to keep your hair blond is to continue bleaching it when your roots start to show

How do i keep my hair color from fading?

well die it and don't wash your hair for 3 days so the color can settle into your hair. that way it doesn't come out. =]