One way is to use the QueryString collection. You can collect the data on the validatefrm.asp page and send that data back to the addEmp.asp page.
You will have to edit addEmp.asp slightly so it can display the values.
' This is an example only. You will need to do something like this:
<input type="text" name="empName" value="<%= Request.QueryString("empName") %>" />
In validateemp.asp, if a field is empty, just generate the correct URL to be directed to.
strURL = "addEmp.asp?empName=" & Request.Form("empName") & "&empAddress=" & Request.Form("empAddress")
Note, your form names will be different to the ones I used for this example.
Do you understand what I mean?