u/Lavellan115

Hello! I have absolutely no experience dying yarn but I've had a sweaters worth of cascade 220 merino for a few years in a color I now hate. I got it in color 40 doeskin heather which is a light brown, but I'd prefer to have a darker chocolate brown. I know there's lots of stuff out there on how to dye yarn but I haven't seen anything about dying pre-dyed yarn. Is it even possible? Am I better off just buying new yarn in the color I actually want?