Great question, but the answer is easy. You need to get more comfortable riding switch. The best way to do that is like learning a new language, immerse yourself in it. Do entire runs or ONLY switch riding. Skate switch, ride the lift, to the carrot, poma, t-bar, or magic carpet, whatever, ALL SWITCH.
Do these things and before you know it you will be landing those 180's with more confidence than ever before!