EIGRP send periodically the update of route table to directly connected routers. Updates are send every 90 seconds. If there is not update after 270 seconds, the route will be marked as inactive. If there is no update after 630 seconds, the route will be deleted from the route table. Also you can change the updating timers using a "timers basic" command.
Router(config)#router eigrp 200
Router(config-router)#network 192.168.1.0 0.0.0.255
Router(config-router)#network 192.168.2.0 0.0.0.3