Return to a part of the program on Arduino

I would like to know how to go back to a part of the program. In this case I'd like to go back to when s1 is read:

const int s1 = 6;

const int s2 = 7;

const int s3 = 12;

const int m1 = 8;

const int l1 = 11;

int cont = 0;


   void setup() {

// put your setup code here, to run once:



  pinMode(s1, INPUT_PULLUP);

  pinMode(s2, INPUT_PULLUP);

  pinMode(s3, INPUT_PULLUP);

  pinMode(l1, OUTPUT);

  pinMode(m1, OUTPUT);

  Serial.begin(9600);


    while(digitalRead(s1) == HIGH){
    Serial.print("Valor de S1 = ");
    Serial.println(s1);
    }
  digitalWrite(m1, HIGH);

 }

void loop(){

     if((digitalRead (s2) == LOW) && (cont < 20)){
       cont ++;
       Serial.print("número de vezes em que o botão foi pressionado:");
       Serial.println(cont);
     }

 else if((digitalRead (s2) == HIGH) && (cont >= 20)){

 digitalWrite (m1, LOW);

   digitalWrite (l1, HIGH);

   delay(5000); //tempo para o LED permanecer acesso

   digitalWrite (l1, LOW);

 }

}