Queen Elizabeth II is not doing the job to break records. She said: "my whole life, whether it be long or short, shall be devoted to your service and the service of our great imperial family to which we all belong."
Of course not -- she is doing it to serve her people. However, there's no reason people can't celebrate these milestones. Surely, she would have rather had a shorter time on the throne if it meant that her beloved father could have lived longer, but that just isn't what happened, sadly.
As she has already achieved long life, the conventional prayer for "Long Live the Queen" may no longer be appropriate. Old age is not for sissies.
I can't see any reason people SHOULDN'T continue to pray for her health and longevity. After all, her mother made it to 101. She certainly doesn't seem so ill that she would be better off dead, which is what you seem to be suggesting, unless I am reading you wrong.