Reload page body when clicking a link in a custom header

Try something like this:

<a href="/" class="home-link">FORUM</a>

<script type="text/discourse-plugin" version="0.8.20">
$(function() {
  $("a.home-link").click(function() {
    require("discourse/lib/url").default.routeTo(
      $(event.currentTarget).attr("href")
    );
    return false;
  });
});
</script>

Where you give your link the classname home-link and run a tiny script when it’s clicked to force it to load within the app.