layui upload 在JS动态加载内容后, 点击按钮无反应

/**
* 根据用户选择的不同规格选项 
* 返回 不同的输入框选项
*/
function ajaxGetSpecInput2(spec_arr)
{        

    var goods_id = $('#goods_id').val();
    if (typeof(goods_id) == "undefined")
    {
        goods_id = '';
    }
    $.ajax({
            type:'POST',
            data:{'spec_arr':spec_arr},
            url:"/index.php/admin/Goods/ajaxGetSpecInput/goods_id/"+goods_id,
            success:function(data){
               $("#goods_spec_table2").html('');
               $("#goods_spec_table2").append(data);
               hbdyg();  // 合并单元格
                layui.use(['form','upload'],function(){
                    var $ = layui.jquery,upload = layui.upload;
                    upload.render({
                        elem: '.demoMore'
                        ,url: "{:url('Upload/upload')}"
                        ,before: function(){
                        }
                        ,done: function(res, index, upload){
                            console.log(res);
                            var item = this.item;
                            var getId=item.context.id;
                            $('#up_img'+getId).attr('src',res.data);
                            $('#up_img_url'+getId).val(res.data);
                        }
                    })
                });
            }
    });


}

在append 结束后, upload.render()就可以了