Incline bench plateau

I started doing incline smith machine bench about two months ago. I started out with 35lb plates, and once I could do 10 reps with those I moved up to 40lbs. I got to 10 reps with the 40s and moved onto 45s. I’ve been stuck between doing 5-6 reps with those for a month and not increasing at all. I hit chest twice a week.