I think a modified version of Jillian's suggested approach would be ok. If you had never seen her, it would not be appropriate to ask for a concession. Since she is your ATF and someone you see on a regular, I think it is ok to ask in a nice way.
"Hello sweetpea, I have so enjoyed all of our time together. It looks like you have increased the funds for your time. Good for you! I'm glad you are doing well. I have a set amount to hobby with, and you are now out of my budget. Since we seem to enjoy each other, would you consider grandfathering me? Please do not feel any pressure, if it won't work, no biggie, either way, I cherish the time we have had."
Good luck!