Adding a new row into an existing named range in a macro

[topper]

I analyse some data in a named range using a macro. The name range is set up using

ActiveWorkbook.Names.Add Name:="bird_ni", RefersToR1C1:= _
        "=bird!R17C1:R25C14"

the data set within the R17C1:R25C14 range grows week by week so has now extended outside this range. While the r25 value can be increase manually this is tedious given the number of data sets involved. The r25 value cannot be set to a higher value intially as it will extend the data set into another data set which could cause selection of an incorrect value.

Is there a way to extent the named range by on row each time the macro is run?

I am a new user of visual basic (Excel 2002) I hope this all makes sense. Thanks for your help