Write following code in Page_Load event of the .aspx page and things will be taken care. Every time the user clicks back button from other page to come to this page, the page will be reloaded from server.
System.Web.UI.HtmlControls.HtmlGenericControl meta = new System.Web.UI.HtmlControls.HtmlGenericControl("meta");
meta.Attributes.Add("http-equiv", "Cache-Control");
meta.Attributes.Add("content", "no-cache");
this.Page.Header.Controls.Add(meta);
System.Web.UI.HtmlControls.HtmlGenericControl meta1 = new System.Web.UI.HtmlControls.HtmlGenericControl("meta");
meta1.Attributes.Add("http-equiv", "Cache-Control");
meta1.Attributes.Add("content", "must-revalidate");
this.Page.Header.Controls.Add(meta1);
Thanks