there's a way to alter the field value using a sql query from past definition to new one?
You'll need to perform a database query such as the following.
From 1 to _UE_MALE (assumes 1 = Male)
[code:1]
UPDATE `jos_comprofiler` SET `cb_gender` = '_UE_MALE' WHERE `cb_gender` = 1;
[/code:1]
From 0 to _UE_FEMALE (assumes 0 = Female)
[code:1]
UPDATE `jos_comprofiler` SET `cb_gender` = '_UE_FEMALE' WHERE `cb_gender` = 0;
[/code:1]
Adjust as necessary, would need to be ran directly from database such as via phpmyadmin.