There are a lot of apps that help you keep up with a certain routine. There might as well be at least one to help you break out of it. Most people live very repetitive lives and trying to challenge yourself and come up with something new to do every day is a job in itself. An app could make this easier by providing suggestions from which you could choose or even plan the whole day for you in a way that you'd cover the necessary tasks, but do something differently, try something new whenever there's a window of opportunity for that.
Such an app would first learn your daily routines and patterns that you repeat and then suggest ways how to change them to improve diversity and minimize repetition.
Important thing to note here is that people often resist stepping out of their usual ways because it takes additional effort and causes discomfort, but that's exactly the price to pay for making your life more diverse and interesting. Life without challenges and change becomes numb. This kills the flow of creativity. So the app would not only find ways for you to diversify your life but at the same time serve an encouraging function presenting habit-breaking tasks as a challenging game.
What would this take: A lot about your daily routines and habits can be told just from your digital activity. This would be the easiest for the app to track and learn from - it would see the usual routes you take, where you eat, what places you visit on working days, weekends, where you go for holidays, what products you buy, people you meet, etc. Then it would suggest alternatives according to your likes, finances, etc.
Additionally, the app could learn by directly interacting with the user - the person would dedicate some time to tell the app about themselves and their day in a digital diary manner (conversation form would be the most user-friendly). The program would then serve as an AI personal assistant aiming to bring more colours into your life through your own actions and choices providing suggestions upon which you could either act or not.
Once the user tried some of the app's suggestions they would then give feedback to the app about whether they liked it, how they feel afterwards, etc. The app would learn and try to improve accordingly. Once again - a slight discomfort is an intrinsic part of the process. There could even be levels of difficulty - how far are you willing to go and how different you want your life to be. This whole setting seems to be good for training AI that is oriented towards personal self-development. With time it could become really good at bringing more joy into people's lives.
Such an app initially might not be attractive to everybody, but it's likely to find its audience amongst creative and adventurous types who are willing to step out of their comfort zone.