losing Label text on postback help.....

Hi,
 
I have a drop down list which has a javascript function on the 'select change' to set the value of "Label2" depending on the selection. 
The dropdown and Label2 are part of a search form and when the search button is clicked a gridview is displayed for the user to select a row.  My problem is when the search button is clicked Label2 loses its value (I use the value of Label2 in my querstring : "...._Label2value.aspx?.......").
 Any thoughts on how I can retain the value of Label2 after the search button is clicked?
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