Rebaptism seems to be a new twist. In some cases it seems to be taking the place of repentance (washing themselves clean of their sins in the manner of John the Baptist). In other cases as a way to testify that they really didn't know what they were doing before at the first baptism because they were too young (immature, married a Witness, urged by their parents, peer pressure, etc.)
The real issue here is not whether they, in good conscience, believe that somehow rebaptism is a cure for past failures or lack of real commitment. The issue is how the Society treats these dips for accounting purposes. There doesn't seem to be any Biblical support for rebaptism in connection with repentance. If there was, there would be a lot of Catholics and Orthodox members that would need to go do it again - unless they really knew what they were doing at their christenings.
I still think the Watchtower might be quietly recommending this approach so as to boost their baptism numbers, if not their membership rolls. Like reporting hours in door-to-door service - it's mostly smoke and mirrors.
JV