Hi Tom,
this might not match 100% your needs, but you could use the dialog cards from H5P. There is the option of "Repetition mode" and if learners are honest and they mark the words that they didn't get right, next time they get only those words, if I'm not wrong.
You could then update the exercise by adding new cards or create a new set of cards - I don't know which option would be the best.