If your BGP neighbour is a Cisco unit (and possibly others), it is possible to reprocess all learned routes and new announcements without clearing and retransmitting the full contents of the BGP table. This is known as a "soft reconfiguration," and is supported as of IOS 12.0. This avoids fast route cache invalidation, network service disruption, and other results associated with wiping the BGP table that would normally be undesirable, although it is more memory-intensive:

Router# clear ip bgp <neighbor IP, AS number, or *> in

To trigger a release of updates toward a neighbor in a similar fashion:

Router# clear ip bgp <neighbor IP, AS number, or *> out