Instance can be re-added by calling save() after remove()

lib/Instance.js

@@ -216,6 +216,7 @@ Instance.prototype.remove = Instance.prototype.delete = function(callback) {
 		this.__state.model.collection.remove(conditions, { w: callback ? 1 : 0 }, (function(err, removed) {
 			if(err) this.emit('error', err);
 			else this.emit('removed', this);
+			this.__state.isNew = true;
 			return callback(err, removed);
 		}).bind(this));
 	});