Next time you think of piercing yourself, dont. Thats why people go spend money to get licensed for this stuff. They know what they are doing.
Each individual piercer has a different guideline on whether or not they will pierce through scar tissue. I personally have never been pierced by one that wont, but I know there are some out there that wont. The best thing you can do is call around and ask before you waste time and gas going place to place.
Before you go to get it re-pierced, it is best to wait 3 or so months to ensure that the pervious piercing is fully healed. The last thing you want to do is add another problem on top of an existing problem.
Also, I have been pierced through scar tissue from a previous piercing and it didnt feel any different than tissue thats not scarred.