Hey guys and lads. I've been working out on and off (mostly on) for the past 10 years. When I was in my early 20s I mostly trained to look good but as of the past few years, having a mostly sit down job, I do it to feel good and to stay healthy. As someone who doesn't like change very much, my workouts for the past couple of years have looked very similar and therefore my weights and progress have somewhat remained stagnant. I have enough knowledge and experience to know that change is imperative to progress and have therefore come here to see if some of you can chime in on what I can do as my next routine to really start seeing some positive gains.

I will start off with my stats:
Age 34
Heights 6'1"
Weight 215 lbs
BF unsure (I do have some visible body fat around mid section but in general people refer to me as having a muscular/athletic physique)
Health: good overall, non-smoker, casual/social drinker, some on and off occurring arthritis in lower back but I deal with it and work through it
Diet: Approx. 3200 cal/day, not clean but I will work on improving that, I know what I have to eat it's just getting strict with it
Supplements: Creatine mono (5g/day), weigh protein

My main goal at this point is to execute a new workout routine for the next 8 to 12 weeks which will allow me to increase my lifts and put on more muscle. I will worry about cutting later. I would also like to somewhat enjoy this routine. I can afford to visit the gym 3-4 times a week.

My current (long overdue) maintenance routine:

Day 1
Squats (5 sets, 6-15 reps per set)
Shoulder press (5 sets, 6-12 reps per set)
Rack pulls (4 sets, 6-12 reps per set)

Day 2
Bench press (4 sets, 6-12 reps per set)
Dips (4 sets, 6-12 reps per set)
Pull ups (4 sets, 6-12 reps per set)
BB rows (4 sets, 6-12 reps per set)

Day 3
Deadlifts (5 sets, 6-15 reps per set)
Leg press (3 sets, 6-12 reps per set)
Shoulder Front raises (3 sets, 6-12 reps per set)
Lateral raises (3 sets, 6-12 reps per set)

Day 4
Bench press (4 sets, 6-12 reps per set)
Skull crushers (4 sets, 6-12 reps per set)
Pull ups (4 sets, 6-12 reps per set)
Cable rows (4 sets, 6-12 reps per set)

I enjoy the above program which is part of the reason I've been doing it for so long. I workout each major muscle group twice a week. I try to lift heavy. I execute each rep with proper deep movements. I rest between 45 seconds to 2 minutes between sets. With that being said, I would appreciate to hear your thoughts on what I can try as my next routine. Looking for some of your favourite programs that help you put on muscle. Thanks in advance!