Looping this guessing game continuously

I'm fairly new to java and I was wondering how could I reset this game to ask another number after the user guessed it correctly?

Here's my code so far:

import java.util.Scanner;
public class Question2 {

   public static void main(String args[]) {
      Scanner keyboard = new Scanner(System.in);
         int count = 0;
         int a = 1 + (int) (Math.random() * 99);
         int guess = 0;

      System.out.println("Welcome to the Number Guessing Game");
      System.out.print("Guess a number between 0 and 100 or enter -1 to end: ");

    while (guess != a) {
    guess = keyboard.nextInt();
     count++;
    if (guess < 0 || guess > 100){
     if(guess == -1){
        System.out.print("Thank you for playing the game!");
             break;
      }
        System.out.print("Out of bounds. Try Again: ");
        continue;
    }
    if (guess > a) {
        System.out.print("The number is lower. Try again: ");
    }
    else if (guess < a) {
        System.out.print("The number is higher. Try again: ");
    }
    else if (guess == a) {
    System.out.println("Congratulations. You guessed the number in "
    + count + " tries!");
    }  
   }

}
}