How to clamp opamp output to +-12v when supply is +-15v
You're using an op-amp as a comparator, which isn't all that great an approach. 

Consider replacing the op-amp with an analog switch such as an ADG1419. 

You can either reduce the supplies to +/-12V or replace R3 with two resistors that give you the Thevenin equivalent. eg. Ra = 1137\$\Omega\$ series and Rb = 4550\$\Omega\$ to ground.

Ra || Rb = 910\$\Omega\$ 

15V * Rb/(Ra+Rb) = 12V



If you insist on using a quad op-amp you could add a series resistor and back-to-back zeners before the 910 ohm resistor, but you'll need an op-amp that swings a lot closer to the rails under load than the TL081, and the tolerance on the voltage will not be great. Another option would be a Schottky bridge and a single zener or a TL431 with resistors to set the clamping voltage (at least that would be very symmetrical).