Why is my best friend ignoring me?

[Kelsonelee]

I've just met a really good friend back in Sept'13, since then we've fast became best friend. We used to talk to each other everyday through wechat and hangout every weekend/during public holiday since Sept'13, we enjoyed each other's company, even went on a vacation together. We have had so much fun and so much to shared with each other, we've even exchanged secrets. However, recently she started to tell me to go out and meet some new friends, I've just answered her that “I've already got a best friend like you and a few others that i can hang out with, why should i get more?" then the conversation just stopped there, she remained silent. After a few days, i jokingly told my other friend in front of her that she wanted me to stop sticking with her, so my other friend asked her if it was true or i was just joking, I was hopeful that she would just answer just joking, but instead she just nodded and didn't say anything else, I was hurt but did not say anything. Now, she's starting to ignore me whenever i'm trying to talk to her through wechat, asked her questions but never get my answer answered, but then I could still see her hanging around on facebook. after a few hours she would just answer me that she's tired from baking cookies and lazy to chat because her line was bad, couldn't send out messages(for a few days). I begin to get upset with her, asking her what's wrong that would lead us into this situation, all she replied me was "why should we keep chatting to keep this friendship going?". So i told her that "why don't you re-read and re-think what you've told me and what I've told you? to keep chatting is not my point at all" she then replied me "i'm lazy to re-read and re-think I'm really tired" I love her as a friend, as a sister, i don't want to lose her...what should i do?