Weekly Copying over 7000 files from Local to SharePoint Library

Sorry I am a bit new, each week I am just copying the same folders to sharepoint so that I get the most upto date file listing.  I do not think this is the best approach as it probably creates alot of unneccessary API calls?  Is there a way to do it better so that I just move new files only or ones that have just been added?  I dont realy have an eazy way to do this as this contains folders then a lot of subfolders so for me to see which one is new would be alot of work.  How can I do this better?