In order for NG to be able to run search queries, it needs a search database. Since this must be based on your product data, this information has to be imported first. Once the product data has been imported, NG generates the associated search database automatically; users can then carry out search queries.
Changes to your product data are only available to FactFinder once the data has been re-imported. Therefore, if you want to refresh your search database with new product data outside the normal update interval, you need to start the manual data import process.