Extends Isotope, providing a reset() method to empty the grid and reLayout.

jquery_isotope_reset.js

// Adds a .isotope( 'flush' ) method to your Isotope widget.
// This method will remove all items from the widget and from the DOM,
// then trigger a reLayout.
$.Isotope.prototype.flush = function() {
  this.$allAtoms = $();
  this.$filteredAtoms = $();
  this.element.children().remove();
  this.reLayout();
};