A couple times now, I've gotten a text/call day-of or day-before a first date that goes something like this:

Her: Oh my gosh! Something unhappy and unpleasant came up all of a sudden--I have to help my dad out/finish that damn paper/whatever. I'm so sorry! You must think I'm so unreliable... Me: OK. Hopefully we can get together soon.

Obviously, it's possible she's telling the truth when this happens, but it feels like a really obvious shit test (yes, I think you're unreliable, because you're being unreliable!) and it's not one I have any idea how to answer. What's the proper response here--terse and empty, chastising, what?

Also, given that she's typically a young attractive woman (hence why I asked her out) it's not like she has to chase people. So, clearly, if I want to see one of these girls again ever, I need to make another attempt at contact--but how? It feels wasteful to just give up on anyone who flakes on a date, but texting her back the next day or whatever to reschedule seems weak and beta and likely to get me perma-canceled on.

If it's relevant, I'm a 22-year-old graduate student, and am typically asking out women my age or younger, themselves in grad school or college.