Why is it that when a ZigBee device, or at least in my case with Sonoff devices, that when the battery runs out you have to delete the device and then rediscover it? Or am I missing something 
Are you using ZHA or Zigbee2MQTT (or even deCONZ)?
I’ve never needed to delete and re-pair a device with Z2M. At most I have to push the little pair button to get it to check in.
Might depend on the device.
I’ve read something like this. Not experienced it so far.
I am using the Sonoff ZigBee V3 dongle plugged into my HA server.