asp net Button Onclientevent fires only once

I got a gridview with items that can be selected,  in the same row I got a textbox where the user must to insert a value and the asp button becomes enable then. Once the asp button is enable, I'm using onclientclick to execute a confirm window with JavaScript creating a dummy input element and saving the answer (yes or No).
if YES, on onclick ="myBtn_OnClick" is executed in code behind where I'm reading the answer (Request.Form["confirm_value"]).
if the answer is NO, I'm saving the rowItem in a variable and refreshing the page with ( Response.Redirect(this.Request.RawUrl);) this is to force the full post back (no partial postback that fires up the Input control), then after loading the gridview I'm searching the rowItem and modify the style and adding the previous text inserted.
This works good for the first try, when I'm clicking the submit button again, it shoul ...