Same problem, I resolve it with this trick, the code is verbose and just an exemple, optimize it !
// functions container
var doc = 
{
    doPopover : function( item_id, title, content )
    {
        // get jq item
        var item = $('#' + item_id );
        // the trick to "refresh content" in every call
        item.attr('data-content', content);
        // popover
        item.popover(
        {
            title   :   title,
            trigger :   'manual'
        }).popover('show');
    },
    popoverFirstCall : function()
    {
        this.doPopover('myDiv', 'Title', 'MyContent1');
    },
    popoverSecondCall : function()
    {
        var content = 'xxx'; // get the content in Ajax
        this.doPopover('myDiv', 'Title', content);
    }
}
// call funcs in your views
$(document).ready(function()
{
    // first popover with first content
    doc.popoverFirstCall();
    // this event wich call the ajax content and refresh popover. 
    $('#button').on('click', $.proxy(doc, 'popoverSecondCall'));
});
I suppose the trick is the same to refresh title also.
If you have a better solution, plz tell me !
EDIT : 
I continued investigation,
we can see on plugin code : 
getContent: function () {
      var content
        , $e = this.$element
        , o = this.options
      content = $e.attr('data-content')
        || (typeof o.content == 'function' ? o.content.call($e[0]) :  o.content)
      return content
    }
so, content is taken on attr "data-content", or on options given at the first call (instanciation) of popover.
But, actually, probleme is, options are cached and not refresh on every call, so wa have to use : 
$('item_id').attr('data-content', 'some content'); // and warning, it is different than
$('item_id').data('content', 'some content');
And bootstrap get the attr way.
Same for title :
getTitle: function () {
      var title
        , $e = this.$element
        , o = this.options
      title = $e.attr('data-original-title')
        || (typeof o.title == 'function' ? o.title.call($e[0]) :  o.title)
      return title
    }
So, doPopover function could be :
    doPopover : function( item_id, title, content )
    {
        // get jq item
        var item = $('#' + item_id );
        // the trick to "refresh content" in every call
        item.attr('data-content', content); // do not use data() way.
        item.attr('data-original-title', title);
        // popover (trace first call if you want)
        item.popover(
        {
            trigger :   'manual'
        });
        item.popover('show);
    }
Work fine for me.