We have the ability to create and cycle through as many levels as we'd like, but this'll get repetitive quite quickly if we don't increase each level's difficulty over time.
The best ways to increase a level's difficulty (at least for PacMan style games) is to:
Make the ghosts faster
Make the ghosts come into the game quicker
These are a few changes that surprisingly aren't that "difficult" to implement. Let me show you exactly how I'd do so myself.