If your Zigbee Router devices work properly then should be no need to re-pair as the mesh fixes itself.
As mentioned, one common issue is poor reception / interference on the side of the Zigbee coordinator.
Suggest you begin by follow some of these general recommendation before troubleshooting any further:
I would start by adding a long USB extension cable to get the Zigbee Coordinator a bit further away, and of course, make sure that you upgrade to the latest recommended firmware on your Zigbee Coordinator adapter.
As well as buy and add a few known good Zigbee Router devices (like the IKEA Tradfri Signal Repeater).
Also read the generic tips here:
Another tip is to shield your computer and USB devices or peripherals connected to computers as well as other appliances or cables/wires located close to your Zigbee Coordinator. As already established if you read those other tips, Zigbee radio can be very susceptible to electromagnetic interference (EMI, also called radio-frequency interference or RFI), and one very common source that generates electromagnetic fields is unshielded computers and unshielded peripherals so make sure that you use for example enclosures for external hard drives and single-board-computers that are made of metal instead of plastic. Especially known to have a huge interference impact on wireless devices using radio frequency like Zigbee radios are USB 3.0 devices/peripherals (for more details on that read white paper report on the subject by Intel at https://www.usb.org/sites/default/files/327216.pdf).