Chart source data gets longer every day? How can I make the chart follow it down?

I have an external add-in to Excel that prints data every day, which increased the data range by 1 cell per day.
I have charts running off this data, but the frustrating thing is, every single day I have to drag down the source data range so that the chart includes the new information. I have attached an Excel file to help explain this. Does anyone know of a way that I can somehow make the chart automatically refresh to include the new data/rows.

Thanks so much, this drives me crazy.

excel help.xlsx

http://peltiertech.com/Excel/Charts/...umnChart1.html

Thanks, i tried this but unfortunately when I get to the stage where I have to click on the chart, and write the named range in the SERIES: bit of the chart in the formula, I type in the name, but it obviously doesn't like it as it doesnt let me escape the formula bar. Any idea? thanks