Don’t make life painful for yourself. You do not have to delete and readd devices. If you purchase some new Zigbee repeating devices, get them paired and into the SmartThings system so you know that they work.
Then, you will unplug the power to your SmartThings hub, take out the batteries (if you installed them), go fix yourself a sandwich and a drink, wait 30 minutes.
Then put the batteries back in, plug the power cord back in and let SmartThings boot back up. At this point in time, a Zigbee heal will occur. Nothing you have to do other than be patient. It’s possible that it could take up to 24 hours for this to complete, more likely less time with as few devices you have.
Did I mention that you don’t need to delete and readd your Zigbee devices for them to find another device to repeat through? Just checking.