Highlight searched text on IFrame using jQuery in ASP.Net

Hi

I want highlight a keyword on all the places in a particular page.

But only 1st word is highlighting.

Please help

page1.aspx

protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
{
    string search = ((HiddenField)GridView1.SelectedRow.FindControl("HiddenField2")).Value;
    Session["search"] = search;
    Session["text"] = TextBox1.Text;
    Response.Redirect("searchresults.aspx");
}

 page2.aspx

<asp:HiddenField ID="hfWord" runat="server" />
<asp:HiddenField ID="hfHTML" runat="server" /> 
<asp:MultiView ID="MultiView1" runat="server">
    <asp:View ID="View1" runat="server">
        <div id="dvDetails" class="fullScreen">
            <iframe id="frmDisplay" name="fileframe" runat="server" frameborder="0" style="width:101.5%; height:99.9%;"></iframe> 
        </div>
    </asp:View>
</asp:MultiView>
<script>
    $(function () {
          var searchWord = $("#hfWord").val();
          var iframeHtml = $("#hfHTML").val();
          var index = iframeHtml.indexOf(searchWord);
          if (index >= 0) {
               iframeHtml = iframeHtml.substring(0, index) + "<span id='lblHighlight' style='background-color: yellow;'>"
               + iframeHtml.substring(index, index + searchWord.length) + "</span>" + iframeHtml.substring(index + searchWord.length);
          }
          $('#frmDisplay').contents().find('body').html(iframeHtml);
          if ($('#frmDisplay').contents().find('#lblHighlight').length > 0) {
              $('#frmDisplay').contents().find('#lblHighlight')[0].scrollIntoView()
          }
      });
</script>

if (!this.IsPostBack)
{
    if (Session["search"] != null)
    {
        //this.Label4.Text = string.Format(Session["new"].ToString());
        hfWord.Value = Session["text"].ToString();
        //txtbk.Text = Session["new"].ToString();
        getsearch();
    }
}

public void getsearch()
{
    SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["connString"].ConnectionString);
    string search = Session["search"].ToString();
    SqlCommand cmd = new SqlCommand("select vcFilePath from tblBookNodes where iNodeId='" + search + "' ", conn);
    conn.Open();
    SqlDataReader dr = cmd.ExecuteReader();
    if (dr.Read())
    {
        bytes = (byte[])dr["vcFilePath"];
        conn.Close();
    }
    getfile();
}

public void getfile()
{
    string search = Session["search"].ToString();
    string text = Session["text"].ToString();
    // string bstxt = Session["bookmarktxt"].ToString();
    string fileName = search.Replace(" ", "_") + ".htm";
    //string returnpath = "File/htmlFile/";
    string strPath = Server.MapPath("~/htmlFile/");
    if (!Directory.Exists(strPath))
    {
        Directory.CreateDirectory(strPath);
    }
    string path = strPath + fileName;
    var doc = new HtmlDocument();
    string html = Encoding.UTF8.GetString(bytes);
    doc.LoadHtml(html);
    StringWriter sw = new StringWriter();
    var hw = new HtmlTextWriter(sw);
    StreamWriter sWriter = new StreamWriter(path);
    sWriter.Write(sw.ToString());
    doc.Save(sWriter);
    sWriter.Close();
    //string fileContents = html;
    string searchText = HttpUtility.HtmlEncode(text);
    string newBookmarktag = " <a> " + text + " </a>";
    html = html.Replace(searchText, newBookmarktag);
    //fileContents = fileContents.Replace(searchText, newBookmarktag);
    System.IO.File.WriteAllText(path, html);
    hfHTML.Value = System.IO.File.ReadAllText(path);
    Page page = (Page)HttpContext.Current.Handler;
    MultiView control = ((IETM.searchresults)(page)).MultiView1;
    View View1 = (View)control.FindControl("View1");
    HtmlControl ctrl = (HtmlControl)View1.FindControl("frmDisplay");
    frmDisplay.Attributes.Add("src", HttpContext.Current.Request.Url + "/.." + "\\htmlFile\\" + fileName);
    MultiView1.SetActiveView(View1);
}