Dropping your working weights sounds like a good idea. As for adding more work, what other pressing exercises are you doing? You could add flys, some tricep work like dips or skull crushers, maybe close grip bench. Just do them for higher reps, like 8-12, maybe 10-15 for flys. If you are going to add more bench sets then start with one or two each day and do them for higher reps, like 8-10. Start conservatively, if it's easy then add another set the next week.
How are you progressing the weights in this program, is it 5lbs. on each lift? If that's the case then you can expect bench to stall first, but still you could add some more volume because 10 sets a week is pretty low.
You can post a video of your bench too, if your technique isn't great then making some adjustments can make a big difference.