Should I continue with the effort to get in touch or should I just leave it?

i think you should text her and say "hey, hows things? i'm a little disappointed you didn't text last night. do you still want to meet up sometime? if so i think you should find a free day and stick to it because i'm getting kinda tired of you cancelling all the time" if she doesn't reply or says another date and cancels again, i would just leave it and get in contact with other old friends, good luck!