You could try to make yourself the lucrative candy box, which she cannot have all the time she wants. You need to stay on top of the relationship and control her implicitly, not explicitly.
Keep her interested by not giving too much of yourself to her at all times. Know how to keep your distance by e.g. not spending every weekend with her, so that she'll miss you more. Do this independently from if you really have something else to do or not. If she asks what you are doing instead, you don't have to lie: just tell her you need to take care of something or that you are tired and like to be alone tonight etc.
If you text message with her on your mobile, or by IM, be careful how you spell out your messages. If she thinks of you while you are not with her, she will probably text you stuff like "I miss you <3". When she does, do not fall into the trap of replicating her message by replying "I miss you too<3" every time. That's giving her the reply she expects. Instead, reply something like "I know. We'll meet at thursday."
We don't know what you are doing already, why don't you tell us a little something about that?