Important caveat before I start: This isn't meant to say you should keep wasting time on girls that aren't showing interest in you. This isn't justifying any sort of oneitis.
I know personally, there are a few girls that I've #-closed and texted back and forth, but they just didn't seem very interested at the time. Either their schedule was busy or they just keep making weak ass excuses. So of course naturally, I move on. However, in my experience, I've found that after a few months sometimes, it doesn't hurt to hit these girls up again.
Maybe it's because absence makes the heart grow fonder, maybe these girls have realized nobody more awesome than you is going to show interest. Who knows. Whos cares. Regardless, I've found that sometimes these girls are much more receptive the second time around. Girls that I've tried maybe 3-5 times to set up a date, (not 3-5 flakes), suddenly are texting back instantly right off the bat, and making time to see me to make a date.
I was surprised that after a long time of radio silence, how eager some of these girls were. So give it a shot, let me know how it works for you guys.
Again let me stress, don't keep wasting time on uninterested chicks. This is more something along the lines of, "Hey I'm taking a shit on the toilet right now, I haven't talked to HBX in months, wonder what she's up to?". Send her a short, witty, funny, or interesting text. It's just a short text you sent while taking a dump. What do you have to lose?
there doesn't seem to be anything here