When saving DOM elements to variables there may come a time when these need to update.

jquery.update.js

(function ($) {
    $.fn.update = function () {
        var newElements = $(this.selector, this.context), i, oldLength = this.length;
        this.length = newElements.length;
        for (i = 0; i < this.length; i++) {
            this[i] = newElements[i];
        }
        for (; i < oldLength; i++) {
            this[i] = undefined;
        }
        return this;
    };
})(jQuery);

// Usage
var dom_variable = $('.my-commonly-used-els');
dom_variable.update();