Greetings, thanks for playing!
There are plans for an easing-in of the more difficult aspects of gameplay in the works for a post-jam update.
In the meantime, your high score is displayed next to your current score in parentheses at the top right corner of the screen.
If it doesn't persist between reloads/retries and stays at (0), that's a bug and I'd love nothing more than to squash it! :D