Crossword puzzles are a great way to recycle new vocabulary and, as you will quickly discover, students usually love doing crosswords.
If you do a search for 'crossword puzzle makers' with Google, you will find there are hundreds of free crossword programs on the www that you can download and use to make your very own crossword puzzles.
I use a program which cost me a few euros, but seems to be able to pack more words in the grid than most of the free software and it also lets you define the size and shape of the grid and type of puzzle you want to make, e.g. a word search, cryptic, clue in box, etc.
I must admit that I got a bit carried away when I downloaded my first crossword program and began using it.
Don't go mad and dish out crossword puzzles for homework every lesson, but don't miss out on a great way to recycle some of the vocabulary you have been teaching.