How to get jqGrid reload to go to server?

You are not the only person which has the problem. I answerd to the same question before. To reload the grid content from the server you should reset the datatype parameter to original value “json” or “xml” and then refresh the grid. For example

jQuery("#list").jqGrid('setGridParam',{datatype:'json'}).trigger('reloadGrid');

UPDATED: To call the line inside of beforeRefresh event handler you can do following

jQuery("#list").jqGrid('navGrid','#pager',
  { edit:false,view:false,add:false,del:false,search:false,
    beforeRefresh: function(){
        alert('In beforeRefresh');
        grid.jqGrid('setGridParam',{datatype:'json'}).trigger('reloadGrid');
    }
  });

I modified an example from am old question. Here if you click on the refresh button you can see live how the code work.

UPDATED 2: Free jqGrid supports some new options. reloadGrid event supports fromServer: true parameter which can be used to force reloading of data from the server and navGrid supports reloadGridOptions option which can be used to specify the options of reloadGrid used on click on Refresh button. So the above code could be

$("#list").jqGrid("navGrid", {
    edit: false,
    add: false,
    del: false,
    search: false,
    reloadGridOptions: { fromServer: true }
});

By the way one can use navOptions option of jqGrid to specify default options of navGrid (see the wiki article). It allows to write the code something like

$("#link").jqGrid({
    // all typical jqGrid parameters
    datatype: "json", // or "xml"
    loadonce: true,
    pager: true, // no empty div for page is required
    navOptions: {
        edit: false,
        add: false,
        del: false,
        search: false,
        reloadGridOptions: { fromServer: true }
    }
}).jqGrid("navGrid");