What to do when girl is not into me after 1st date?

Okay!

First meeting: I met this girl in the same company I use to work for. We just exchanges 'HI' for the first time, but then she asked me 'To have lunch with her'. We hang out together for like 3 times as a normal co-worker. Then I left my job and joined different firm.

First Official Date: So, after joining different firm, I asked her out like as an official first date. The date went pretty good. We took a walk after dinner (actually she insisted!) then I dropped her off at her place. I hugged her and gave a gentle kiss on her lips. After leaving her, I texted her like 3 hours later that "I had a great time and have a good night". But after that, she is behaving like aloof, by not replying to my texts frequently. When I text her today, she will text me back tomorrow or something, which really annoys me!

So, my last text to her was: "We should cook lunch/dinner together, say Thursday at 7?". She replied: "That sounds fun! But I cant do Thursday". So, I said "Too bad, but I understand. Well, let me know when is the good time and we will plan accordingly". She said: "Okay! Sounds good ". Its been 3 weeks and I havnt got any reply from her.


My question is: What should I do at this moment? I really like this girl and she is a keeper. Can someone please advise!