Auto Refresh of Now() function

Hi All,

I am using the now() function in on of the excel sheet to get the current date and time. My problem is that when ever i read the data from this column i am getting the date and time of when i saved the excel. But i want the cureent date and time i.e the time when i am reading the data from the excel.
I appriciate your help to resolve this.

Thanks in advance.
ss.