The BH ReRange is the normal process for the BH registration process. The Backhaul Master (BHM) starts with an initial small frame and waits until the Backhaul Slave (BHS) first attempts to register. The BHM detects the distance of the BHS, and fails its registration telling the BHS to ReRange. The BHM configures a new frame with the exact distance of the BHS so that no airtime is wasted.
If you are seeing ReRange in your logs please know this is not the cause of your problem, but a symptom of your link going down and coming back up. We would need to look further into why the BHS is losing its link the first place. Check the power and radio uptime. Check for VC errors, perform a link test and check uplink and downlink efficiencies for possible sources of interference.