Hello Ian,
no, if you stop the UPL and start it again, nothing will not be deleted )
Just restart it.
then run the FM again. As soon as it shows good status, wait for extractor run.
Hope is runs fine.
I doubt it will fetch the data.
By the way, is the data available in St03n for 14.09.2014?
I think you shouldn't concentrate on 1 day.
By the way, I suppose the table is so enormous (dozens of GB). You'd better not to keep so much data. We recommend 14 days only.