I have two excel sheets - File1.xls and File2.xls

File1 has data in which new rows are added every now and then and the previous data is updated every now and then. The data in File1 is used as an input to File2. So, what I want to do is to have some trigger, pressing which, my File2 will have the older data updated and new data being arranged in File2.xls. How can this be done?