This app was mentioned in 2 comments, with an average of 2.00 upvotes
https://play.google.com/store/apps/details?id=com.justinguitar.app.TimeTrainer
I recently found out about Time Trainer Metronome which allows for dropping bars/beats as well as tempo increase over time. Heard about it on the Drummer's Resource Podcast.
Google Play Store Link
Apple App Store Link