help: excel Data/chart link

Your help will be appreciated:


I created an excel file (file A) that contains data from 12 excel files via links, then made a chart that has different ranges based on the data in the 12 excel files (most of them have different ranges), finally did some statistics based on the data from 12 excel files. The things are that every time I need to open the 12 excel files in order to get the statistics correct and let the chart shows all the new data from 12 excel files in the file A. My question is what I should do to get the data and chart updated automatically without opening the 12 excel files?

Thanks,

littlenut