This may sound strange but give it a thought.
The two of you have some history even if it was a long time ago. Did she sound sincere on the phone? She must have if you two made plans for this.
Since it's been so long since you have had time to visit you may hit it off again and be great friends or this might be a big yawn fest. Who knows?
If you meet and find that you would like to hang out again, there's time for that in the future. What you are trying to do now is just test it out to see for certain.
Make it a point to set something up in that area during or directly after you are supposed to meet with your friend. Nowdays with the way that people in general cant keep an appointment to save their asses this will allow you to have a good time doing something completely different if she cancels or no-shows on you.
If you show up at the given time and place and things dont go well, no bigge, you have something infinitely more interesting and fun to all set up. If for some reason she's rude, not giving you the attention that you deserve for making that time for her, asking you for money, or any other unpleasant possibility....disappear. Go do that thing that you **really** wanted to do in the first place.
If you both end up having a good time and spend hours and hours and hours catching up and reliving old times just pass on the plan B.
Either way you are covered.
Just remembered another thing. If someone cancels or no-shows you once....statistically speaking they will again ( and again and again and again ). If she no-shows you and still wants to set something up again....have her send you $20 in the mail that the two of you will spend on lunch when she shows up on the next brunch.
Cancel on Slang one time....no biggie....try to set up another deal, there is a deposit required.
and.....have that $20 ready to send if you no-show her....you dirty girl!