BGP soft reconfiguration
When BGP routing policies are changed within a BGP router, it is necessary to reset the BGP session before the policy takes effect. A hard reset using the clear ip bgp command will tear down all BGP peerings and reestablishes them.
The soft reconfiguration feature, also known as soft reset, lets the router request its BGP neighbor to send its prefixes again, without tearing down the peerings.
This can be configured using the soft-reconfiguration keyword in the neighbor command.
Links
https://networklessons.com/bgp/bgp-soft-reset-reconfiguration