Convert your data on Sheet1 into a Excel Table by selecting a cell inside the data set and press Ctrl+T and that will convert your data set to an excel table.
Now insert your pivot table based on your table. The advantage of this is, whenever you add new data on Sheet1, just go to Sheet2 where you have inserted the pivot table, right click inside the pivot table and select Refresh, and your pivot table will reflect the new data which you added on Sheet1.