what do you wish to change it to?
changing the voltage is easy, doing so without affecting its temperature profile is a bit tougher.
the easiest way is to generate a bandgap current and run it through whatever resistor load you want(modifying the voltage in the process)
Well adjusting the amplitude of ur bandgap reference depends on the type of ur reference.
If it is in a type that it first sums PTAT and CTAT current and then conducting this current through a resistor to generate voltage with low TC, in this way u have to change just the resistor to adjust ur final voltage(assume that resistor doen not have temperature dependancy).