If you did understand what you were doing as a child, which is possible, then no need to be rebaptized again.
Could it be that you have grown substantially in your walk with Christ and have a better understanding of what it means to be a Christian as opposed to when you were a child?
That would be a natural progression in the walk and the sign of a maturing Christian. Paul wrote about this in Philippians 3 when he wrote about pressing on toward the upward call.
Hope this helps.
Feel free to freepmail with more questions.
You got it pretty close. I was maybe 6. I knew and understood... but I just went threw the motions, just waiting for it to be over so I could get back home and ride my bike.