Sure, though I never really *DID have a childhood because I had no friends on my street but instead were 5 miles away which made things difficult. If I could relive my childhood and I knew exactally what I knew now, I would have, like said above do what would have been a good idea and NOT do what was a actually a bad idea. Also I could prevent a LOT of accidental data deletion on my computers and know exactally what to do when a problem occurs and not have to wait 5 years later to figure it out. I also could have prevented many more stupid purchases like my dad buying the bose sound system or devices getting fried like my first laptop.
Also re-living my childhood wouldn't be so terrible despite bad times because I would know exactally what to do/how to prevent it and how to overcome it easily. Like if I remember one particular fight that happened when I was 7 for example because I did something, I could either do "my bad thing" at a later time or not at all. Life would be a peice of cake, it's like having a guide to your own life because you already experienced things. You could even make smart purchases because before you were unsure or didn't know about one particular product.