Opposite of night light, on in day off at night
When the photo cell reaches 0.6V = Vbe, the LED starts to dim towards off.

This is 4.4V/2.2k= 2 mA 

To reverse the direction of control with 2mA , replace the cell with 0.6V /2mA = 300 Ohms assuming threshold was OK before. Increase for more sensitivity on a cloudy day.

Then replace 2.2 K with photo sensor.