auto update of a chart

Hi,
With a line chart ,I used to update data table by adding a row data every
day.After that I update source data--data range of my chart by manually
increasing a row number.Example:on 20/jun/06 my data range =sheet1!
$a$1:$b$25.on 21/jun/06 my data range changes to =sheet1!$a$1:$b$26.
Is it possible to put a formula in data range to automaticalyy select source
data from data table.

try if u can use some of this 1:

http://pmexcelent.dk/DynamicShart.xls