What is the data source? I have a few different data sources setup here that do a full refresh on weekends but do incremental refresh during the week for the same data source? Is that what you are trying to do?
The other possible thing to do is call the refresh from a local copy of Tableau and publishing to the server - using the command line - Tableau Data Extract Command-Line Utility .
This is especially handy if you have a Tableau Server in a location that can not directly reach the data source from the server.