If you have recently experienced some cycle irregularities, the app may not send you recommendations to test for LH anymore, as it would mean that you would have to take a lot of LH tests.
If you don’t see any LH recommendations, just keep logging your temperature regularly. The recommendations will return if your cycle becomes more regular.
You are welcome to take LH tests even on days when the app doesn’t prompt you. The best time to test for LH is in the days leading up to your predicted ovulation – learn more here.