Renewing kerberos ticket without user intervention
kinit -R seems to do the trick for me. I'm tempted to suggest just having a LaunchAgent that runs this command with a StartInterval of, say, 7200 seconds (2 hrs); you could get fancier (e.g. testing network connectivity first, adjusting the retry frequency as your TGT gets closer to expiring, etc), but I think you'd mostly be going to a lot or work to avoid a tiny bit of computational expense.