Arduino Script Issue?

Hey world, I am making device that will automatically water my xmas tree: I am using the basic "button" script from the Arduino IDE examples. the only change I have made so far is instead of using an actual push button I am sticking 2 bare copper wires(the ground has a 10k resistor) into a jar.  When water is added to the jar the connection is made and the LED goes on. The problem is that it only stays on for like 7 seconds. I need it so as long as there is water in the cup the light stays on. any ideas? Below is a copy of the script. Thanks!

const int buttonPin = 2;     // the number of the pushbutton pin
const int ledPin =  13;      // the number of the LED pin

// variables will change:
int buttonState = 0;         // variable for reading the pushbutton status

void setup() {
  // initialize the LED pin as an output:
  pinMode(ledPin, OUTPUT);
  // initialize the pushbutton pin as an input:
  pinMode(buttonPin, INPUT);
}

void loop() {
  // read the state of the pushbutton value:
  buttonState = digitalRead(buttonPin);

  // check if the pushbutton is pressed. If it is, the buttonState is HIGH:
  if (buttonState == HIGH) {
    // turn LED on:
    digitalWrite(ledPin, HIGH);
  } else {
    // turn LED off:
    digitalWrite(ledPin, LOW);


Don't look continuously at the pin, just wake it up once every few minutes for a second or two, see if there's a connection, then return to 0V.

+1