CONCAT_WS

SELECT
    CONCAT_WS(
        ',',
        SUBSTRING_INDEX(
            '1,2,3,11,13',
            ',',
            FIND_IN_SET('1', '1,2,3,11,13') + (
                CHAR_LENGTH('1,2,3,11,13') - CHAR_LENGTH(
                    REPLACE ('1,2,3,11,13', ',', '')
                ) - 1
            ) - (
                CHAR_LENGTH('1,2,3,11,13') - CHAR_LENGTH(
                    REPLACE ('1,2,3,11,13', ',', '')
                )
            )
        ),
        'NEW VALUE',
        SUBSTRING_INDEX(
            '1,2,3,11,13',
            ',',
            FIND_IN_SET('1', '1,2,3,11,13') - 1 - (
                CHAR_LENGTH('1,2,3,11,13') - CHAR_LENGTH(
                    REPLACE ('1,2,3,11,13', ',', '')
                )
            )
        )
    )