Sorry, I really don't understand what you mean. How is using a voltage divider going to increase the voltage? If the output is 1.25v in relation to the adjustment pin, how do I get it up to a higher voltage?
I was thinking that since the output is 1.25v above the adjustment (which is floating and not grounded), and the adjustment always sources a constant current, I could use a resistor to ground to "set" the adjustment pin to a particular voltage using Ohms law. Since the current is constant, and I want, for example, 5v, I could choose a resistor that would satisfy 5v = 75 uA * R, thus setting the reference adjustment pin at 5v, and the Reference output at 6.25v (all in relation to the common ground).
Then I could use those voltages with a divider to set the high and lower bounds for the LEDs