I'm not an Alumna (yet), but I understand the importance of encouraging inactive alumnae to "come home". I think the problem is worse in NPC chapters than NPHC, but it is still annoying to find out that there are alumnae living DOWN THE STREET from you, but don't do anything with the sorority.
I know we have membership incentives for those who "come back", especially if they do work with the local collegiate chapter (one of the things that suffer with decreased alumnae activity). But, as I forgot to say, I don't like the emphasis (even in collegian chapters) on getting NEW members, when your CURRENT members are shady at best!
It's best to work with what you have NOW, as opposed to trying to start anew with a fresh batch. I support having intake for alumnae every other year (or less, depending on the size and interest).
Best of luck...it seems this problem is UNIVERSAL.