HELP! Bleach over highlights? Root touch-up?

So I have been getting my hair bleached and getting highlights for years now, and my hair is pretty blonde from the highlights. It still has a little dimension though, but overall pretty blonde. My natural hair color is a light brown/sandy blonde, not very dark. My roots are darker than I would like, and I can't afford to go to the salon right now so I am planning to bleach my hair at home this time, but I do not want to use foils.

If I were to do a root touch-up by applying bleaching only to my roots and use toner all over my hair, would the colors match, or would it clash since I still have some dimension in the rest of my hair? If I put bleach on all my hair (including the previously bleached hair) would it match and blend well? Or would the ends be lighter than my roots?

BTW: I know bleach does tremendous damage to your hair, I will be using coconut oil to cut the damage down, so I'm not too worried about a ton of breakage.