When I used to use red chemical dyes, they did fade quite fast. So If you're not coloring again until the end of the year, it might not be a problem to just dye over.
There are different products that are focused on getting chemical dyes out. I think one of them is Color Oops? That might help when you want to get the last bit of red out.
I hope this helped. I'm not really experienced in this, except for a couple times I dyed over myself. Good luck!