Have you checked out Nicole Allison's AMAZING
Leveled Vocabulary Intervention? If you haven't you should finish reading this post, then go check it out! I was lucky enough to get to try it out with some of my students, and it was a total hit. I really like how it provides a framework for teaching vocabulary that spans several different categories/word parts including: antonyms, synonyms, homonyms, prefixes, suffixes, and context clues.
The "Say, Teach, Example" increasing levels of complexity across each category make it really easy for you (the therapist/teacher) to build on the skills students acquire during therapy! I found the pages with pictures really beneficial when first introducing the concepts. My students LOVED drawing on the interactive pages (I put them in page protectors so they can be used repeatedly).