Since you have a set of 11 speed comp. wheels, for the cost of the replacing a with a new set of 10 speed lever you might as well jump to 11 speed.
6800 group went as low as 500.00 bucks with merlin, I pick it up at 505.00

On the other hand if your are not ready to spend, a set of replacement 10 speed shifter can be had for under 150.00
Tiagra 4700 STI shifters runs for under 150.00 new I seen at at the 130 range. since you are running 6700 you dont need to worry about mushy brakes.

Used 6700 shifters is commonly in the 150 range, if you hunt you can likely score an entire group in the 300 range.
Used 5700 shifters is even less.

if you are going to keep the frame for a while go 11, if you are not just replace the lever