Updating Smartsheet from external sources

I have a task list (for want of a better term) that was made in SharePoint and shared with many users. They make updates. I then export to Excel, import to Smartsheet and do what I need to to make an informative report.

I can't remove the SharePoint element from this process.

I need a way to update some of my information (2 or 3 columns) from the external source without having to rebuild the whole Smartsheet again. It looks like this will be a regular activity.

Suggestions would be greatly appreciated.