Adding new columns to the data: ALTER TABLE
At the start of the project, if you're OK with deleting the database and recreating it, then stick with that. But there is a better way.
SQL has a ALTER TABLE command that lets you modify the table without losing
the data it already contains.
Here's the SQLite documentation on ALTER TABLE (includes syntax diagram).
con.execute("ALTER TABLE buggies ADD COLUMN power_type VARCHAR(20);")
Although you could update init_db.py to modify the table in this way, that
seems wrong because you're no longer initialising it.
Instead, you could make a new file (maybe something like update_db.py?) to
run. You'll need the same preamble to connect to the database that init_db.py
had.
But then you have a problem because maybe in the future you'll need to add even
more columns, and adding them to this file won't work because ADD COLUMN may
cause errors if you try to run it on a database table that already has that
column.
So it's not uncommon to end up with a file for each change... these changes are called migrations. Often the migrations are timestamped or named with incrementing numbers (because the order they are executed in a new installation may be important). Read more about database (or schema) migrations.
Python has a module called Alembic that manages database migrations. That's probably overkill for this project (but it is being used on the slightly more complex buggy race server).