Adding meta refresh tag

Using Arduino Networking, Protocols, and Devices
1

I've been having problem on adding this tag

<meta http-equiv="refresh" content="2" >

so that the webpage displaying my sensor data would refresh every 2 second but error message always popup.
Can anyone tell me how to do this correctly

String SendHTML(float temperature,float humidity,float pressure,float altitude, float distance){
  String ptr = "<!DOCTYPE html> <html>\n";
  ptr +="<head><meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0, user-scalable=no\">\n";
  ptr +="<title>Test Sensor Station</title>\n";
  ptr +="<style>html { font-family: Helvetica; display: inline-block; margin: 0px auto; text-align: center;}\n";
  ptr +="body{margin-top: 50px;} h1 {color: #444444;margin: 50px auto 30px;}\n";
  ptr +="p {font-size: 24px;color: #444444;margin-bottom: 10px;}\n";
  ptr +="</style>\n";
  ptr +="</head>\n";
  ptr +="<body>\n";
  ptr +="<div id=\"webpage\">\n";
  ptr +="<h1>Test Sensor Station</h1>\n";
  ptr +="<p>Temperature: ";
  ptr +=temperature;
  ptr +="&deg;C</p>";
  ptr +="<p>Humidity: ";
  ptr +=humidity;
  ptr +="%</p>";
  ptr +="<p>Pressure: ";
  ptr +=pressure;
  ptr +="hPa</p>";
  ptr +="<p>Altitude: ";
  ptr +=altitude;
  ptr +="m</p>";
  ptr +="<p>Distance: ";
  ptr +=distance;
  ptr +="cm</p>";
  ptr +="</div>\n";
  ptr +="</body>\n";
  ptr +="</html>\n";
  return ptr;
}