Problem: 

How to reset BGP peering and re-announce BGP routes.  Inbound traffic is supposed to traverse through the preferred ISP.  However, traffic splits between different ISPs after maintenance or short outages.

Solution: 

Clear BGP sessions to update BGP routes after an outage or maintenance.

Command: 

     clear bgp neighbor soft

This processes re-announces BGP routes to upstream neighbors. Clear a BGP session whenever inbound/outbound policy changes are made; or after outages or maintenance.

CISCO Juniper Routing