Might be worth considering that just because you have enjoyed having her as your regular, it doesn't mean she has actually enjoyed having you as her regular. She may have raised her rates and deliberately not grandfathered you in because she doesn't actually want you as a client anymore, but also doesn't want the hassle of refusing your booking requests or explaining.
Let's face it - if she doubled her rates and deliberately did not grandfather you in, she obviously doesn't give a shit if you stay as a client or not, 'regular client' status be damned.
Some girls just get tired of certain clients and want to move on. Could be because you've grown too attached, she's bored with your sessions, you are making demands of her she can't/doesn't want to accommodate...tons of reasons SP's fall out of love with their regular clients.
The rate change is sometimes just a means to less than obvious end. And sometimes you just have to take the hint.