thicker spokes do nothing but add weight.
A spoke almost NEVER breaks in the middle, always at the elbow.
I would never run anything bigger than a double butted 14/15/14 spoke, and that's what I had on my old mountain biking wheels.
Large guy's don't necessarily need to run 36 spokes. I have a 230 pound friend that rides a 32 spoke wheel on his mountain bike (Chris King hub laced 3x on Sun Rhynolite rims with 14g straight gauge spokes), and he rides almost as hard as me.
What you should do is take the wheel to the shop. Have them rebuild the wheel with 14g straight gauge spokes in a 3x pattern. If I'm not breaking spokes at a 75 rating on the Tensionometer, you won't be doing it on a road bike.