I used to dye my hair brown, I hadn't dyed it for a few months when I decided to dye it red. At first it was OK, but after about 6 weeks the top 2-3 inches are lighter & the ends (shoulder length hair) are nearly black with a red tint. I want to dye it again with the same red but I don't want the ends to be so dark. I use head & shoulders shampoo as I get dandruff, I think that night be why the top has lightened so much, but I don't know what to do about the ends... Any ideas?

When you dye your hair only die the new growth that is why your ends are so dark and your roots are lighter, if you want to give your color a boost take equal parts of shampoo and color and wash it in then rinse it out. But put color on the new growth only