I want to be careful here. It is certainly possible that a person might look back and see that the reasons they were baptized were insincere and their obedience to the gospel wasn't really from the heart. If that is your case, I don't want anything I say here to deter you from obeying your conscience. If I happened to be at your side, I would encourage you to be baptized and would even offer to assist you in doing so.
That said, I must also tell you that I'm a bit uncomfortable with the number of "rebaptisms" that I hear about. I appreciate the sincerity that prompts an individual to take such a step (knowing the agony of conscience that is usually involved, I always advise that one's conscience should be followed), but I wonder if an improvement in our understanding might not help us. Think with me here . . . carefully.
Here is the situation that often arises: when a sermon has been preached on, say, commitment or counting the cost of discipleship, it's not uncommon to hear someone say, "When I was baptized, I didn't understand much about commitment, and I wasn't as serious about turning to the Lord as I should have been. Do I need to be rebaptized?" Usually my answer is, "No, what you need to do is begin living on the basis of the deeper commitment that you have right now."
When we obey the gospel, we make the most important commitment of our lives. The only thing comparable to it is the marriage vow. So what would you do if, some years after being married, you recognized that your commitment to your spouse was not what it should have been? Would you think you needed to go through another marriage ceremony? No, despite your immaturity and lack of commitment, you have been married the whole time. You don't need to get remarried; you need to start acting on the basis of the commitment that you made.
Yes, there are couples who may decide to "renew their vows," but no one seriously thinks that they were not actually married before. What is happening here is what ought to happen when we realize our commitment to the Lord has been lacking. Having learned a deeper commitment, we commit ourselves to being more faithful in the future.
Like it or not, when we enter into commitments, those commitments are binding upon us even if we were less than sincere when we "signed the contract." The time may come when we need to be more serious about the agreement, but unless it was fraudulently made, the contract has been binding all this time. We just need to get a fresh grip on our duties.
As for your baptism, I hope that you'll be learning new things about commitment for the rest of your life, but you won't need to be rebaptized every time you reach a new level of maturity. Believe me, I know what it's like to feel the need for a "fresh start." But for the Christian, a fresh start does not mean rebaptism. It means repentance.