Reusing Workflow with Excel Reader

I have built several workflows that use an Excel readers. I complete the workflow and everything works as expected. When I receive a new data set, even though the schema on the new file matches the workflow, the workflow rescans the new file and changes all my data types in the Excel reader. (By default I set all columns to string - wish there was a way to set this as a perm default, but thats another topic).

Is there a way to prevent the Excel reader from changing the schema when pointing to a new file?

Thanks for your help…