You have to use jQuery to achieve this feature
First apply some identifier to your data container
<div id="reportContent">
@Html.Partial("PartialView")
</div>
And then write script on your dropdown change event using jQuery
<script type="text/javascript">
$(function(){
$("#ServiceLine").change(function{
// get data from server using ajax
var url = 'YourPartialPageURL?'+serviceLine+="="+$(this).val();
$('#reportContent').load(url);
});
});
</script>
Note: You should use return PartialView(); from your controller action And don't use @Html.Partial and use @Html.Action instead. @Html.Partial loads View directly without going to Controller Action. It should be used if you have data to be passed with you or if you just want to load some static content on the page