bleached hair dark roots grows

Hello.
I bleached my hair 3 months ago, little by little my natural hair color is growing.
It doesn't look good anymore so I am not sure what to do.
should I rebleach just the roots?
I was thinking to go hairsalon to do just roots blond, but maybe it can be expensive.
Anyone knows how much it can cost to dye dark roots at hairsalon?
I live around osaka.

:)

To lighten your roots starting price is around 4000 yen and salons insist on charging for the whole head of hair despite the roots only needing the bleach, and 4000 yen is a starting price, because many salons charge a price of 8000yen, and some places I went to took several hours to bleach my hair, one place took 3 hours just to bleach roots, and none of the salons toned my hair after bleaching it so it looks bright orange-yellow after leaving the salon. I live in Kansai too like how you mentioned you live in Osaka, and this has been my experience. I don't blame the salons for all this though because not many Japanese people dye their hair blonde, and the few Japanese people that dye their hair blonde do not tone the orange/yellow out of their lightened hair so it ends up looking anime blonde. So I gave up going to the salon since its expensive and time consuming, and roots need to be dyed often, so I just buy a box of Fresh Light mega-mega-bleach (the box with the Blythe doll on it, also Palty bleach is an option too) and dye it, it usually only costs 500-800 yen a box and only takes me an hour total to dye my roots (that includes applying the bleach by standing in front of a mirror, putting a shower cap on it, waiting with the bleach on my head, and taking a shower afterward), and you can buy lavender (purple color toner) shampoo at Donkihote to use all the time after dyeing your hair so that your hair looks natural blonde rather than orange or bright yellow. At first I was not so good at bleaching my hair myself, but after I kept doing it I got better at it, and it's so easy now when I bleach at home that I realize it's such a waste of money to go to a salon for something so simple.

Thank you for the reply!
I bought box of hair dye lucido-L ash blonde color and I did it at home.
It turned out well!
Even the dark roots are beautiful color now!
I am surprised by the result :)

From now on I just do it at home :)

Thank you!