I've mentioned this old BB'ing trick (lifting is full of little tricks to boost you along) about counting higher reps and making them seem lower, a couple of times before. This helped me years ago when I was into 20+ heavy breathing squats mostly. For me anyway, lifting can be as much a mental effort as a physical one. Have to get the mind set for any serious lifting.
If your rep target is 12 (for example) than try something like this. Instead of counting 1, 2, 3, 4, etc, add the word "and" between each numbered rep.
Example: 1..and..2..and..3...and. ..4..and...5...and...6.. .the final "and" will be the 12th rep. This can very from set to set, at times the last rep may not end on "and" but a number. No problem, adapting to this rep scheme is quite easy, reducing the mind into thinking that lower reps have been done just by the number count.
This counting rep trick also works extremely well on lower, heavier lifting, not just higher reps. If doing sets of 3's you will be counting 1..and..2 and your done with the set which actually means you have done 3 total reps for that set.
Good Luck..