How can I even out my hair color?

I have dark brown hair naturally but I dyed it light brown. a couple months later I dyed it ash blond over top of the light brown. the color looks great except the roots are slightly darker and redder. I'm just wondering if theres a way to get it all one color...I left dye on roots for the recommended longer time than the rest of my hair...should I leave it on even longer? or possibly wait a week or two and dye roots again?

wait a bit to dye just your roots