I dont want to sound harsh but why is this so hard for her? She loves you, misses you but still cannot decide if she wants you?
I hope by going out with her its not going to set you back if she then decides that she is still confused.
Are you meant to wait until she is ready again.
I guess if you love her you will wait, but make sure you are not just being pushed to the side lines until something else comes along.
Go out with her and be yourself, enjoy the night and dont get too serious as it may make the night awkward. Just be you, no mind games as I am sure you know they dont get you anywhere.
I feel for you because if i put myself in your shoes I would feel nervous of the out come . Let us know how you go.