I've been hanging out with this girl but idk her mindset yet. I asked her to hang tomorrow and she said she has an event thing tomorrow but has extra days free this week so she will "hit me up." usually the "I'll call you" is lack of interest but the way she said it has me second guessing. we were being playful and flirty right before so I honestly dont know if she will or not.

OK - before we start hating on the girl and assume the "hard to get" scenario... You stated you were being flirty and playful. You also stated you are just "hanging out" with this girl and want to "hang" again. These are all super super casual scenarios. Which means, "I'll hit you up" would fit right in with those scenarios. So she's just going off what you're insinuating.
If you want a more deliberate response, meaning, you know you want to see her again and maybe progress to something more with her in the future, say it. Unless you guys are 18 and still in high school, be up front with how you feel. You'll save yourself so much BS by just being up front, like "this is fun, I'm having a great time, and how about we keep it going and I take you to ------ next week"
If you want a more deliberate response, you need to be more definitive and confident in what you truly want and tell her. Not every girl likes to F off like the first responder fool said. A lot of us would rather do without the BS as well and be real. Good luck