I have a workbook with a tab that has charts and data. Because the
number of data points can vary month to month, I have set up the chart
to reference named ranges. The named ranges are columns that vary in
length, defined by language like this:

"yvals"=OFFSET('MainSheet'!$B$2,0,0,COUNTIF('MainS heet'!$B$2:$B
$20,"0"),1)

"xvals"=OFFSET('MainSheet'!$A$2,0,0,COUNTA('MainSh eet'!$A$2:$A$20),1)

The X and Y series use the named ranges. If I add or remove data the
chart range automatically changes accordingly. These named ranges have
a scope that is only within the sheet, not a workbook scope.

What I want to do is be able to copy the worksheet and duplicate it.
Each month I get new data, so I copy the worksheet and modify the new
worksheet.

What I find is that when I copy the sheet (in Excel 2007), the new
chart has replaced the named ranges with absolute cell references. But
the names on the sheet do copy over correctly.

How can I do this where the new chart retains the named ranges? I
don’t want to manually re-create the chart series each time (I have a
lot of charts).

Thanks