No, you can go ahead and move on to the next week's exercises. I couldn't do 36 of some of the exercises at first either. The focus of ladders is to do as many as you can, but with good form. You'll improve quickly and get faster.

Stick with it - my husband and I are finishing up week 9 and have had great results so far!

I don't really get why the iPhone app limits you to 36 rep... Even when I started basic, and was way out of shape, on leg day I was doing in the 60+ rep range for squats (at 250lbs of bodyweight!) xD The point of ladders is to build some muscle endurance as well as proper form, so you do what you can, but there is no use to stick to it past the first 2 weeks. If anything, the intervals are easier after that (where your goal WILL be completing 36 reps of each exercise total). And then supersets may look scary, but they're even shorter workouts so it balances out

Do know this, though: if you're following the app and are female, there's a good chance your upper body will be far behind your legs to begin with (and heck, middle of 1st class here and I'm still lagging). That's completely normal. Keep going through the program. Adjust the difficulty of some exercises if you have to (I still bend my knees doing let me ups, for example). I've found leg day was always when I could push myself the farthest, I feared push day for quite a while (decline push-ups can be a scary thing, and my triceps aren't super strong), and most utterly hated the pulling exercises (and still do) because I have rubbish grip strength (and arguably a bad setup, lol). Core days seem to be very mellow throughout though haha.

The only block you should repeat is the last 4 weeks (that include the infamous stappers) of a program if you feel you're not ready to move on to the next level yet. Or you can do another program and then come back to the next level later like I did