I precedent this with I have never had an older rabbit, nor any specific knowledge.
What I can say is increased hay consumption is never a bad thing. If your mini red female is still seeming quite healthy, I’d still go ahead with the usual hay. Can you mix different types of hay in the new brand hay to compensate? And if not, I’d be against putting more pellets, as the rabbit should learn to eat the new brand hay, even if it’s not as good.
Aside from diet, how often do you see your vet for regular exams?
— and lastly, 7.5yo was surely filled with lots of joy and happiness. I’m sorry for your loss, and your clear effort to go further with your female shows a lot of love for rabbits and their lives. Binky free lovely bun.
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.