As per screenshot, when there is change in the date range so in the onChange listener of datepicker, you should refresh the list "SourceDataPointList" for the pie chart. It will refresh the chart on the screen.
Like in below example : there is one input field "Number Value" and there are 2 elements in my pie chart "First" and "Second". When Number Value get change then OnChange of NumberValue chart is getting refersh. Same way you need to refresh the chart data on datepicker date chagne.
Hope it helps. If any confusion let me know.

