The start and end dates could be references to other cells in the workbook. Their values shouldn't be replaced if the query is not modified from the sidebar. The same applies for other cells in the configuration sheet, all the configuration could be dynamically generated. What's the need of replacing the values on each refresh?
Both start date and end date are only modified in a refresh when the date range is a predefined interval (e.g: last month, last 1 week, last 2 years, etc...). If start date and end date are static, they will not change with the refresh.
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