is she not interested ?? how to deal with her ?

i have been talking to this girl for a while. we went out several times. she studies in my uni but she lives in another country. so now in the summer vacation the only way of communication is texting. she always replies instantly to my messages. on her birthday i sent her funny picture i made for her. she liked it and she said thank you so much and she put it as her profile picture. a day later she sent me a text saying " hey Kevin look i put the picture you made for my birthday as profile picture". we continued to text each other but one day she read a message that i sent but she didn't reply for 24 hours. i sent her another message about a different topic and I didn't mention at all the fact that she ignored me , she replied to my message and then she said was tired on the bed the whole day. i personally didn't buy this. we continued to message and she still replies instantly. then after two weeks of instant replies again one day she ignored my text message. it shows read yet no reply after 24 hours. in these 24 hours she changed her profile picture and i thought she is not interested. i played it very cool and sent her a message joking about how she is taking too much time to respond. she responded instantly but I ignored her to see if she would message me . one day later she sent me this " hey are you still alive?"

this is confusing why when I ignored her she tries to get my attentions is she playing hard to get or not interested? and how to deal with her is it because i didnt make a move and what she is expecting from me ?