Web Forms :: Refresh The Result After Calling A Dll?

I was writing a program in C#.net and in my program, I was calling a dll as following:

Program.EigenDLL(FilePath,
n, c1, c2, step);
done.Text =
"Successfully done";
title.Text =
"N = "
+ n + ", C1 = "
+ c1 + ", C2 = "
+ c2 + ", Step = "
+ step;
StreamReader
StreamReader1 = new
StreamReader(Server.MapPath("eigenvalue.txt"));
Result.Text = StreamReader1.ReadToEnd();
StreamReader1.Close();

These code is in an onclick event and they work perfect, but after I change the input values and click the button once more in order to call the dll again, the result shows up is still the result I got last time. I konw in windows form, I can use process.refresh() to solve this problem. My question is: how can I do this in a webform?