Situation:
I originally met this girl at the start of the college year, number closed, and we texted back and forth a bit (admittedly, my game near the start of the year was shit). She would reply immediately to the first text, but then stopped replying just in the middle of conversation (though her responses seemed to get shorter over time). Knowing this was going nowhere, I just dropped her number from my phone.
Fast forward to a couple of weeks ago, and she texts me out of the blue, in the middle of the night, saying "Hey it's [let's call her Sarah]! this is my new number

" We exchange a few texts, and I just decide not to reply after one of her texts because it was too late and i was with friends. When I reply to her message the next morning, she immediately responds, and asks for my facebook. Since she couldn't find me, I ended up adding her later in the day. We've since exchanged a few texts, where she usually replies immediately, but each time, she just stops responding in the middle of the conversation (I don't think it's that my texts are boring AFC -- however, it could be that I'm always too silly and never serious =/).
Now:
After a week of not talking, I text her out of the blue with
"Sarah! Did you join the army or something? I haven't seen you in ages

"
She immediately replies with (literally less than a minute after)
"LOL I KNOW.. No, no army joing tho hahaha"
I responded:
"Whew!- not sure if you would last out there, gotta keep someone like you safe y'know"
She hasn't responded since. Can this situation be salvaged? Or do I just cut off this lead. (Keep in mind I did that 2 months ago, to have her randomly text me a couple weeks ago). Also, delete facebook?