How do we refresh the new updated fresh database with the old database without replacing the database?

Old Database would be the client database and we cannot the directly replace the database on the client database as it will consist live data.

Our requirement is to refresh new changes on on the old database without hampering the client live data.

Its likely to be an project upgrade.Can someone assist me on this,how can we achieve this without using any third party tool.

I am aware how to achieve this by making manual script. But is there any other way that we can implement this more smoothly,as it will be happening very often and running

manual script will be time consuming.