Refresh data from formulas

[BIT.Society.06]

Hi,

I have an excel workbook with two sheets: data and summary.
I have a seperate program that inputs data directly into the data page.
There are formulas in the summary page that then total the data and
give a number value. each of these formulas calls a user defined
function.

The problem is that when the data is input and the file loaded, the
summary fields are not updated with new values. I must click on each
one to refresh them.
Is there some way to have the sumary page automatically refresh this
data?

I'm using excel 97.

Thanks!