Wella - Color Not Carried - Switch to What?

I have been coloring my hair with Wella 5RG and 6RG 50/50 for many years. It's basically an Auburn color. Sometimes it can look brown, and outside it looks basically red. I want to stop pulling the color through as often and thought about just doing a toner to brighten it up and hopefully make it look more shiny. I was thinking of 7RG, but it is no longer available in this line. I don't know what to do. I am open to switching brands altogether knowing that there will be a learning curve, different formulas, or whatever. Any ideas?