For whatever reason, it's probably real hard to progress on bench after losing a lot of weight for average people. I'd say the most progress I ever made consistently on bench was back when I did it at least 2X up to 3X/week, doing pyramids working up to a max. Followed by bentover rows, lat pulls, and CLOSEGRIP BENCH PRESS (VERY IMPORTANT! -- same as regular bench, but move hands as close together as thumb tips touching the other hand, or thumb tips-to-tip, or inside edge of hand resting on beginning of knurl outside of smooth part of the bar).
If you can find a Camber Bar, it has a big bend in the middle so when you lower the bar to chest, your hands are far lower than in the normal BP -- increases the range of motion (ROM) by around 12 inches, greatly increasing your starting bench strength.
Powerlifters usually use bench shirts, which make you so much stronger at the start of the bench that, for the most part, Westside-style lifters focus much more on triceps -- lockout strength -- relative to training only starting strength. Average "real-world" bench-pressers, who usually don't wear bench shirts, need to focus on their starting strength.
IMO, the 3 biggest keys to increasing bench for non-shirted bencher:
1) Max reps at least 1X/week
2) Closegrip bench -- heavy weight, low reps
3) Camber bench press or something else that increases ROM