It’s frankly up to you. There are some folks that don’t repeat any lesson. Others like to repeat. Or, what I found in the beginning stages, say when doing the mini-stories, or similar (like Assimil) I would repeat the lesson several times over the course of a day or two (not all at once). With each reading I would hope to understand all the words. After those handful of readings, I would move on, even if I hadn’t gotten all the words “memorized”. I did this because I’ve found that some words stick easy and some don’t and it’s better to just move on and not get bogged down on the words that don’t stick. You’ll add many more to your vocabulary if you move on. You’ll improve extremely slowly if you let the “un-sticky” words become your barrier. Also, I found that after reading a lesson a few times, I felt like I had memorized the story and therefore it wasn’t really useful anymore.
Keep in mind that you’ll see the most common words over and over in different lessons, so moving on to the next lesson is not the last chance you’ll ever see those words again.
I also think moving on is dependent on the length of a lesson. Ones that are a few minutes or less (of audio) lend themselves to repeating. They are short and sweet. Longer lessons that are 10 minutes are more, to me, are less repeatable. At least for reading. I’ve read it, (or slogged through it) and I’m ready to move on to something else. If I do want some repeat exposure to words in the longer lessons, I’ll just go back and hop through, yellow word to yellow word. Reading the word in context and trying to guess at it again. So, kind of like “flash cards” except I have the word(s) in context.