Not much you could do unless you are prepared to pay her 1 month notice.
My bun bun is also leaving next month, I told her I would give her a very good reference letter to keep her motivated, since she needs my reference letter(she planned to move to UK), she is a bit slow and only do the basic chores, but it's acceptable lah, even for HK people, after we hand in our resignation letter, we would be not so hardworking too ma!
我鐘意你同我講 I Love U, I Love U Too!
You are the sunshine of my life. That's why I'll always stay around. You are the apple of my eye. Forever you'll stay in my heart.
But remember if you release her earlier than the contract finished date, then her insurance is still under your shoulder, i.e. if anything happened to her, it's your responsibility ga!