How do I get my ex girlfriend to miss me? I never call her but she calls me once or twice a week, do I have to play hard to get and just be laid back and after a while maybe she will be more interested me.

You can't make somebody miss you, they just do! Or maybe that should be they either do or they don't.
Instead of beating around the bush and wasting time, why not just tell her you want her back and see what she says? If she says no, move on.

Honestly, too much manipulation as to what you should do or what you should not do in a relationship only leads to more confusion... rather I would suggest instead of being too emotional about things, try to have open communication with the opposite party and above all take things slow... let it all flow on its own... that should be strategy.