1. Make the student(s) randomly have to present their results on a weekly basis. If you get caught for cheating at this point, at least in my uni with a zero tolerance policy, you instantly fail the course.

2. Make take home stuff only a requirement to be able to participate in the final exam. This effectively means cheating on them will only hinder you and not affect your grading directly.

3. Make take home stuff optional and completely detached from grading. Put everything into the final exam.

My uni does a mix them on different courses. Especially two and three though have a significant negative impact on passing rates as they tend to push everything onto one single exam instead of spread out work over the semester.