Can a voltage divider circuit be used before regulator to reduce heat?
Your idea of using a voltage divider is not viable at all. You have to dissipate the power in a linear regulation system somewhere, and typically would do this in the regulator.
....but you could add a series resistor to drop the voltage at your target load current ...this would spread the dissipation between the regulator and the resistor. You still have exactly the same power dissipation however, and you have to make sure you don't exceed the current limit you used to select the resistor. 

You could also use a Zener diode or set up a pass transistor with a smaller resistor to allow you to spread the dissipation between multiple devices. This can work, but again you are simply spreading the power dissipation between devices instead of providing a heatsink for the regulator.