You should use a while loop: The dice are rolled again and again until the player has won or lost (then, break
ends the while loop).
while (true) {
int dice1=(int)(Math.random()*6+1);
int dice2=(int)(Math.random()*6+1);
int sum = dice1 + dice2;
System.out.println("Roll: total = " + sum);
if (sum==2 || sum==3 || sum==12) {
System.out.println("Sorry with a " + sum + " You LOSE :(");
break;
} else if(sum==7 || sum==11) {
System.out.println("Woah!!! With a " + sum + " You WIN!!!!!!!");
break;
}
// If you wanted, you could wait here for the user to confirm (e.g. with a key press)
}