I want to wash away all my sins. I want a fresh new start in life. Can I be baptized again?
As we say in the Creed every Sunday: "I confess one baptism for the forgiveness of sins."
We get this from St. Paul who told us that there is "one Lord, one faith, one baptism" (Eph 4:5).
And the Church teaches clearly in the Catechism, paragraph 1272: "Incorporated into Christ by Baptism, the person baptized is configured to Christ. Baptism seals the Christian with the indelible spiritual mark (character) of his belonging to Christ. No sin can erase this mark, even if sin prevents Baptism from bearing the fruits of salvation. Given once for all, Baptism cannot be repeated."
However, fear not! We receive a "fresh start" each time we go to the sacrament of confession with contrition for our sins. Catechism, paragraph 1446: "Christ instituted the sacrament of Penance for all sinful members of his Church: above all for those who, since Baptism, have fallen into grave sin, and have thus lost their baptismal grace and wounded ecclesial communion. It is to them that the sacrament of Penance offers a new possibility to convert and to recover the grace of justification. The Fathers of the Church present this sacrament as 'the second plank [of salvation] after the shipwreck which is the loss of grace.'"