DHT22 Does not update Good evening :)

I am fairily new to coding the fabulous Arduino UNO. My project right now are consisting of reading Temperature from a DHT22 (AM2302) and writing to a 4-digit 7-segment display. I have got the display to work, but the system does not update the temperature at all. Just the first reading are displayed

#include &lt;DHT.h&gt;
  #include &lt;TimerOne.h&gt;
  #include &lt;SevenSeg.h&gt;

  #define DHTPIN 4    //Defines the temp-pin

  /* DHT22- Pin1 (left) - 5V/3.3V
  Pin2- DATA
    Connect a 10K res from pin1 to pin2
  Pin3 - NC
  Pin4 - GND
  */

  //#define DHTTYPE DHT11   // DHT 11 
  #define DHTTYPE DHT22   // DHT 22  (AM2302)
  //#define DHTTYPE DHT21   // DHT 21 (AM2301)

  DHT dht(DHTPIN, DHTTYPE);

  SevenSeg disp (13 ,2 ,3 ,8 ,5 ,6 ,7);
  //            (11, 7, 4, 2, 1, 10, 5)
  const int numOfDigits =4;
  int digitPins [ numOfDigits ]={9,10,11,12};  // uten transistorer
  //                            (12,9,8,6) Alle med 220 Ohm seriemotstand
  //int digitPins [ numOfDigits ]={12,11,10,9};  // med transistorer

  void setup () 
  {
    Serial.begin(9600);
    Serial.println("DHT22");

    disp . setCommonCathode();  // uten transistorer
    //disp . setActivePinState(HIGH,HIGH);  // med transistoere
    disp . setDigitPins ( numOfDigits , digitPins );

    Timer1.initialize(15);   // 0.015 sek
    Timer1.attachInterrupt(loop);
  }

  void loop() {

    dht.begin();

    delay(300);
    float t = dht.readTemperature();   

    disp.writeFloat(t);
    Serial.println(t);

  }


How do I get the Sensor to update regularly?
Try moving dht.begin(); to setup(). 

The DHTs are pretty slow and need some time (of the order of seconds!) between consecutive reads. In dht.begin() an internal timer is reset that is used in readTemperature() to ensure that reading data from the DHT is not attempted in shorter intervals than supported. By calling dht.begin() every 300 ms you're making this meachanism inoperative. You're supposed to call dht.begin() only once at start-up.

Edit: And please also remove the Timer1 that calls loop. loop is already an infinite loop, so no good in calling it additionally from an interrupt...