We are using classic cloud service and we have some configurations which are different for staging slot and production slot.
We are thinking to deployment automatically so, is there any way to Don't change configure while swapping server (deployment) ?
It is not possible. Essentially when you swap staging slot with production slot deployment, no changes are done at the Cloud Service Level. Only the Virtual IP (VIP) associated with staging slot is swapped with that of the production slot (that's why the process is called VIP Swap).
You can learn more about swap deployment operation here: https://learn.microsoft.com/en-us/previous-versions/azure/reference/ee460814(v=azure.100).