how to add removed partition? This is the structure of my table:

-- Table: t_keyword_conversion_ga
-- Create Table: 
CREATE TABLE `t_keyword_conversion_ga` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`own_domain_id` int(11) DEFAULT NULL,
`keyword_id` int(11) DEFAULT NULL,
`traffic_date` date DEFAULT NULL,
`targeturl_id` int(11) DEFAULT NULL,
`entrance` int(11) DEFAULT NULL,
`transactions` int(11) DEFAULT NULL,
`item_revenue` decimal(9,2) DEFAULT NULL,
`goal1completions` int(11) DEFAULT NULL,
`goal2completions` int(11) DEFAULT NULL,
`goal3completions` int(11) DEFAULT NULL,
`goal4completions` int(11) DEFAULT NULL,
`goal5completions` int(11) DEFAULT NULL,
`goal6completions` int(11) DEFAULT NULL,
`goal7completions` int(11) DEFAULT NULL,
`goal8completions` int(11) DEFAULT NULL,
`goal9completions` int(11) DEFAULT NULL,
`goal10completions` int(11) DEFAULT NULL,
`goal1Value` decimal(9,2) DEFAULT NULL,
`goal2Value` decimal(9,2) DEFAULT NULL,
`goal3Value` decimal(9,2) DEFAULT NULL,
`goal4Value` decimal(9,2) DEFAULT NULL,
`goal5Value` decimal(9,2) DEFAULT NULL,
`goal6Value` decimal(9,2) DEFAULT NULL,
`goal7Value` decimal(9,2) DEFAULT NULL,
`goal8Value` decimal(9,2) DEFAULT NULL,
`goal9Value` decimal(9,2) DEFAULT NULL,
`goal10Value` decimal(9,2) DEFAULT NULL,
`medium` varchar(255) DEFAULT NULL,
`source` varchar(255) DEFAULT NULL,
KEY `id` (`id`),
KEY `keyword_id` (`keyword_id`),
KEY `traffic_date` (`traffic_date`),
KEY `own_domain_id` (`own_domain_id`,`traffic_date`),
KEY `targeturl_id` (`targeturl_id`)
) ENGINE=InnoDB AUTO_INCREMENT=581732054 DEFAULT CHARSET=utf8
/*!50500 PARTITION BY RANGE COLUMNS(traffic_date)
(PARTITION p201101 VALUES LESS THAN ('2011-01-01') ENGINE = InnoDB,
PARTITION p201102 VALUES LESS THAN ('2011-02-01') ENGINE = InnoDB,
PARTITION p201103 VALUES LESS THAN ('2011-03-01') ENGINE = InnoDB,
PARTITION p201104 VALUES LESS THAN ('2011-04-01') ENGINE = InnoDB,
----&gt;PARTITION p201105 VALUES LESS THAN ('2011-05-01') ENGINE = InnoDB,
PARTITION p201106 VALUES LESS THAN ('2011-06-01') ENGINE = InnoDB,
PARTITION p201107 VALUES LESS THAN ('2011-07-01') ENGINE = InnoDB,
PARTITION p201108 VALUES LESS THAN ('2011-08-01') ENGINE = InnoDB,
PARTITION p201109 VALUES LESS THAN ('2011-09-01') ENGINE = InnoDB,
PARTITION p201110 VALUES LESS THAN ('2011-10-01') ENGINE = InnoDB,
PARTITION p201111 VALUES LESS THAN ('2011-11-01') ENGINE = InnoDB,
PARTITION p201112 VALUES LESS THAN ('2011-12-01') ENGINE = InnoDB,
PARTITION p201201 VALUES LESS THAN ('2012-01-01') ENGINE = InnoDB,
PARTITION p201202 VALUES LESS THAN ('2012-02-01') ENGINE = InnoDB,
PARTITION p201203 VALUES LESS THAN ('2012-03-01') ENGINE = InnoDB,
PARTITION p201204 VALUES LESS THAN ('2012-04-01') ENGINE = InnoDB,
PARTITION p201205 VALUES LESS THAN ('2012-05-01') ENGINE = InnoDB,
PARTITION p201206 VALUES LESS THAN ('2012-06-01') ENGINE = InnoDB,
PARTITION p201207 VALUES LESS THAN ('2012-07-01') ENGINE = InnoDB,
PARTITION p201208 VALUES LESS THAN ('2012-08-01') ENGINE = InnoDB,
PARTITION p201209 VALUES LESS THAN ('2012-09-01') ENGINE = InnoDB,
PARTITION p201210 VALUES LESS THAN ('2012-10-01') ENGINE = InnoDB,
PARTITION p201211 VALUES LESS THAN ('2012-11-01') ENGINE = InnoDB,
PARTITION p201212 VALUES LESS THAN ('2012-12-01') ENGINE = InnoDB,
PARTITION p201301 VALUES LESS THAN ('2013-01-01') ENGINE = InnoDB,
PARTITION p201302 VALUES LESS THAN ('2013-02-01') ENGINE = InnoDB,
PARTITION p201303 VALUES LESS THAN ('2013-03-01') ENGINE = InnoDB,
PARTITION p201304 VALUES LESS THAN ('2013-04-01') ENGINE = InnoDB,
PARTITION p201305 VALUES LESS THAN ('2013-05-01') ENGINE = InnoDB,
PARTITION p201306 VALUES LESS THAN ('2013-06-01') ENGINE = InnoDB,
PARTITION pEOW VALUES LESS THAN (MAXVALUE) ENGINE = InnoDB) */
1 row in set (0.02 sec)


I dropped the partition 'p201105'. Now I am trying to add it again with the below statement but it throws an error:

ALTER TABLE t_keyword_conversion_ga 
ADD PARTITION (PARTITION p201105 VALUES LESS THAN ('2011-05-01'));

ERROR 1493 (HY000): VALUES LESS THAN value must be strictly increasing for each partition


How to add the same partition?
The following seems to work in Mysql 5.5.


ALTER TABLE `t_keyword_conversion_ga` REORGANIZE PARTITION p201106  INTO (
    PARTITION p201105 VALUES LESS THAN ('2011-05-01') ENGINE = InnoDB,
    PARTITION p201106 VALUES LESS THAN ('2011-06-01') ENGINE = InnoDB
);


as you can check by sqlfiddle