Hey guys need some advice

So I know this girl (HB8) a while but never saw her a lot because she living quite far away from me.

We had some small conversations over FB and Texts, in the summer we started to send messages (not chat) so we always had a couple of days to answer and she keeps answering me back and in that summer she sent me a message where she said: " That we really need to go out and she was looking forward to it", I answered: " I'm in! and suggested some dates to get together and go out!" Then she replied that she had a car accident and i just replied something like: " Take care! ... " And then messages started to stop, she once started chatting with me on FB. But it was a small conversation and she only asked how i was and i asked her how she was, so nothing special because i was quite busy that day.

Note: This was all before I discovered PUA

So past month I thought why no send her a message! Which I did and it was something like :" Hey X long time no see! How are you? You don't happen to have a naughty twin sister who does want to party with me? " (Translation is a bit weird, but I hope you guys understand) Couple of days go by, nothing special I knew on FB she doesn't answer always back the day after. And then one week after the message she replied: "hahahh , maybe me? :p Yes indeed long time no see, i'm fine how are you?"

So i read some stuff on text game and so I was going to wait a week to reply, but then i was on a trip and was very busy on projects and stuff and going out, so actually totally forgot about the message. So tomorrow it will be four weeks since she replied.

So now my question is; Should I still answer? Because at the end of the month i'm going to a big party that's not that far away from her home and would like to invite her.

And when I do answer, should I apologize for the waiting? Or just ignore it and answer?

my answer would be like: Oh nice! I really need to get to know your naughty side then! Oh and i'm going to party x with some friends you should really so we can meet again!