void loop() stops running after an hour or so

So I have a program that measures temperature and humidity over time. Here isthe code I use:

#include <SD.h>
#include <SPI.h>
#include <DHT.h>
#include <Wire.h> 
#include "RTClib.h"

#define DHTPIN 2 
#define DHTTYPE 22
const int chipSelect = 10; 


DHT dht(DHTPIN, DHTTYPE);
RTC_DS3231 rtc;


void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  Serial.println("DHT22 sensor reading");

  if(! rtc.begin()) {
    Serial.println("Could not find RTC");
    while(1);
  }

  if (rtc.lostPower()) {
    Serial.println("RTC lost power, lets set the time!");
    // following line sets the RTC to the date & time this sketch was compiled
    rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
  }
}


void loop() {

  //temperature measurements
  float hum = dht.readHumidity();
  float temp = dht.readTemperature();

  if( isnan(temp) || isnan(hum )) {
    Serial.println("Failed to read from DHT22 sensor!");
    return;
  }

  Serial.print("Humidity: ");
  Serial.print(hum);
  Serial.print(" %t");
  Serial.print("Temperature: ");
  Serial.print(temp);
  Serial.println(" *C");

  //determining the date
  DateTime now = rtc.now();

  int dayy;
  int monthh;
  int yearr;

  int hours;
  int minutes;
  int seconds;

  String date;
  dayy = now.day();
  monthh = now.month();
  yearr = now.year();
  date = String(dayy) + String(monthh) + String(yearr);

  int seconds_passed; // how many seconds have passed since the start of the day: used for the data plot
  hours = now.hour();
  minutes = now.minute();
  seconds = now.second();
  seconds_passed = ((hours * 60) + minutes)* 60 + seconds;




  //writing to SD card

  if(SD.begin(chipSelect)) {
    Serial.println("Card is initialized! Ready to go!");
  }
  else {
    Serial.println("Error with initializing the card!");
    return;
  }
  Serial.println("Opening file...");
  String FileName;
  FileName = date + ".dat";

  File dataFile = SD.open(FileName, FILE_WRITE);

  if (dataFile) {
    dataFile.print(temp);
    dataFile.print(",");
    dataFile.print(hum);
    dataFile.print(",");
    dataFile.println(seconds_passed);
    dataFile.close();

    Serial.println("Written data to file and closed it");
    Serial.println(" ");
    Serial.print("Seconds passed: ");
    Serial.println(seconds_passed);
    Serial.println(" ");
  }
  else {
    Serial.println("Error with opening the file, trying again"); 
  }


 delay(1000);
}

It works like a charm, but for the fact that it stops running after an hour, maybe 1,5 hours.

Resetting the board seems to work, but I can’t obviously sit there the whole time and reset the board. I use an Arduino Due. Did I program something wrong that something overflows or should I add some more code?