You don't. It isn't a live connection to the data, and it isn't designed for you to continue editing the results. It's expected to be almost the last stage of production (though there may be cases where tweaking the results or styles is needed).
You change the CSV file and rerun it from the source file, as often as needed.
Well, if you put the placeholders onto the master spread, the resulting merged file will keep the connection to the csv file and the data can be refreshed via the links panel.
But you have to be careful and have a precise workflow where to change what. If you delete or add entries you have to rerun it to a new merged file and then lose all manual changes you may have done in your InDesign file.