How to make your hair color bolder?

[LAgymnast]

ok so i dyed my hair back to my natural hair color (dark brown) in january, but since summer passed it turned into like a dull ugly brown, like it's really boring and i LOVED the bold dark brown/black it was, but i dont want to re-dye it cus i dont want to damage my hair too much so is there something like a product or anythign i can use to get rid of the dull brown to a dark deep bold dark brown? THANKS