Re-import nodes daily using feeds and hook_cron
There is no need to do that manually. 

Under Settings for Node Processor just select Replace Existing Nodes.

For further details you can check https://www.ostraining.com/blog/drupal/feeds/ which explains the steps in detail.

There is a field called GUID. Make sure that you set it to an appropriate value so that nodes will be updated(deleted and reimported). If the GUID in your site matches to that of the import then current nodes will be deleted(irrespective of whether they were created manually or imported) and the nodes from your news source will be reimported.