Qlik NPrinting keeps connection to QlikView documents open after the generation of the first reports to improve performances (reduce the report generation time) while genereting other reports from the same connection. The cons is that if you reload the data into the QlikView document after the generation of the first report you will not see the new data.
When you manually do a connection metadata reload, Qlik NPrinting closes the connection to the QlikView document. When you generate the first report after the metadata reload the connection is opened again and you will see updated data.
So, you have to reload the metadata in NPrintinting after each QlikView reload to get updated data.
The new version June 2017 (internal number 18.104.22.168) lgives you the possibility to trigger metadata reloads. So you will be able to schedule Qlik NPrinting connection metadata reload after the QlikView documents data reload and before report generation without the need of manual actions.