Again I humbly disagree with jsmooth. I hope this doesn't get to be a habit bro
The infamous "ok" reply or any one-word/short sentence reply means her attraction temperature has fallen. When you're in the comfort stage online you MUST keep her attraction up too. This means building comfort but also adding in push/pull bits every now and then and playful teases. Sounds like things have gotten a little stale. You need to bring her back to how she felt when you got her number. A good shock-value story usually does the trick. For example, "omg I saw the funniest thing today..." and end it with a question.
I cant see the convo for myself, so if you believe there's still solid attraction you can just go for another comfort bit. Just make sure it have a question at the end and an easy reason for her to reciprocate a decent reply. Off the top of my head you could say...
"Hey goofball! A bunch of us are going skydiving and you popped into my head...I have no clue whhy but it was a little annoying, so whatever spell you put on me I want it off! Now! You ever notice how there are some people who think they're open-minded and adventurous...and they make all these great plans about meeting new people, or going on a diet, or taking a cool trip. But then they don't...they just sit around doing the same boring shit, over and over again. Are you like that?"
Also, if your phone game isnt good you can get the meet up without ever even calling her....you have to seed the meet up in a message like jsmooth pointed out in the facebook thread, then just use text to handle logistics. But if you're good on the phone then definitely call her.
-V