Hartbeat timeout

One of my sketches works fine for a while then after a Hartbeat timeout the Arduino Nano with ESP8266 hardserial cannot recover. What should I do?

[408650] Heartbeat timeout (last in: 392644)
[408750] Cmd not sent
[410750] Cmd not sent
[416837] <msg 2,1,32
followed by Login Timeouts

#include <SoftwareSerial.h>
SoftwareSerial MySerial(9,10); // RX, TX
#define BLYNK_PRINT MySerial
// Set ESP8266 Serial object
#include <ESP8266_HardSer.h>
#include <BlynkSimpleShieldEsp8266_HardSer.h>
#define EspSerial Serial
ESP8266 wifi(EspSerial);
char auth[] = "auth";
WidgetBridge bridge1(V30);
WidgetLED led21(21);

#include <SimpleTimer.h>
int vacation = 0;
int UP_PIN = V1;
int ALARM_PIN = V11;
bool runn = 0;

void setup()

  // Set ESP8266 baud rate
  Blynk.begin(auth, wifi, "mywireless", "mykey");
  while (Blynk.connect() == false) {  // Wait until connected
  bridge1.setAuthToken("other auth");
  Blynk.virtualWrite(UP_PIN,0);    // turn Up off
  Blynk.virtualWrite(ALARM_PIN,0); // turn Alarm off
  vacation = led21.getValue();
  timer.setInterval(2000L, sendData);

void loop()
  timer.run(); // Initiates SimpleTimer

void sendData()
   Blynk.virtualWrite(UP_PIN,runn);  // turn Up off
   runn = !runn;