Regardless of what you do (adding weight vs. reps, DBs vs. BB), decrease the weight. I know the whole "don't let your ego get in the way of development" thing is a cliche, but dropping the poundage to a point where you can keep good form then working your way up is going to raise your bench faster than starting high and trying to grind out reps with poor/inconsistent form.
Also, if you haven't done so already, look into some microplates.