Display name dont change automaticaly

Display name dont change automaticaly


Hello,
 
i have big problem with my router identification in the network,
we have complete network configur without problem with opmanager version.7005 , i have 1000 device licence.
 
Now problem comes as we are changing HOSTNAME of all router in my network and there are lik 700 routers int my network , it is not UPDATING DISPLAY NAMES IN " SNAPSHOT" page.
 
I have tried to rediscover devices and also update the status but without result ...then i have tried deleting the device and REDISCOVER it again and now it works
 
but i can not delte all the device like this there must be a way to update the display name ...plz guide me to this problem
 
Arpit.