tinymce editor gets disappear on postback in update panel in asp.net

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ASP.NET

I have placed tinymce editor on my page within updatepanel. I have a button(Button1) on this page which when clicked causes postback and the editor gets disappear.
I have also registered that button in updatepanel as:

 if (!Page.IsPostBack)
            {
               ScriptManager.GetCurrent(this.Page).RegisterPostBackControl(Button1);
}

i have to register it because on click of this button i am creating dynamic javascript which is adding menus in editor based on condition. If i don't register, it doesn't update the menus in editor.

Please help me to resolve this..