Update viewdata on button clicks

<div id="newApplication" class="invisible">
     <form id="frmnewApplication" action="">
        <fieldset>
            <ul class="formone">
                <li>
                    <label class="labelone">
                        Name:</label>
                    <%--开发者_高级运维    <input type="text" id="ApplicationName" class="inputtext validate[required]" />--%>
                    <%= Html.DropDownList("ApplicationName", ViewData["AppList"] as IEnumerable<SelectListItem>)%>
                </li>

This is my div. I am fetching the values from viewdata["AppList"]. My dropdown is fetching the values from ViewData in pageload only even though I am updating my viewdata in other controller methods it is not updating the viewdata. Plz help. This is the jquery method

function updateDropdown() {
            $("#ApplicationName").html("");
            $.ajax({

                type: "POST",
                url: "/Shielding/AjaxGetDdlList",
                dataType: "json",
                success: function (data) {
                    if (data == null) {
                        alert("Something went wrong. Please try again;");
                    }
                    else {
                        for (group in data) {
                            var newOption = $("<option></option>").attr("value", data[group].ShieldFirewallApplicationId).html(data[group].ShieldFirewallApplicationName);
                            alert(data[group].ShieldFirewallApplicationName);
                            $("#ApplicationName").append(newOption);

                        }
                    }
                }
            });
        }

This is the controller method:

public ActionResult AjaxGetDdlList()
{
    return Json(ShieldingRep.GetAllApplications());
}

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You may need to use tempdata. try to use viewmodels approach you may get help from this link

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Viewdata isn't persisted between calls. The problem will be found in your controller.