Need help android 4.1.2 to 4.3 Sony xperia acro s (LT26w)) topic

Is there a proper solid way of updating from 4.1.2 to 4.3 android? I kinda have a dilemma, i recieved a sony smartwatch 3 for christmas.. and you need android 4.3 or higher to run android wear.
Please help!
-Chris
thanks in advance