Is It Possible To Go About Rebuilding "Silent" Networks?

My wife and I have had a few discussions over the last year about one particular topic: Why do previous long-term contacts, be they personal (usually) or professional, seem to fall away and go silent? For starters, I'm a parent, so often times it's just not on my daily radar to text, email, or phone a friend to say hello. But I've noticed that the further I get from the last time I spoke with them, the less likely I am to get a response back when I do think to ping them. Granted, everyone's life changes at some point, and surely there is at least one reason they cannot reply within a short timeframe. But after a couple unresolved attempts to reinitiate contact, what next?

This has been a frustration point for me, as I tend to want to keep (most of) the networks I've built up over the years rather than just dropping them. Networks do require maintenance, certainly. After all, I place value in the people I've built friendships with, particularly since high school (20 years ago, eek!). But the sheer number of contacts can make this process unmanageable. Then there are those person-to-person networks from the unconnected, still pre-dotcom era 90s when I was in high school that seem to slowly be making a minor comeback as I approach my 20 year reunion.

I think this is a serious question as I proceed into the future. The reality we live in now is increasingly demanding a diverse and deep set of networks to do almost anything, from finding out things to do with your kids on the weekends, to staffing the latest project at work. Of course this phenomenon doesn't deter me from wanting to build other, new networks regardless, but I do find myself concerned over what feels like lost social capital.

My questions are:

• Have you experienced a sort of communicative "disappearance" of certain individuals similar to the above?
• Has social media helped or hindered your efforts to maintain contact?
• What have these "disappearances" meant for your network(s)?
• If you've managed to reinitiate a "silent" network, What strategy did you use?