from copy import deepcopy
from pathlib import Path
from shutil import copy
import json

journal_path = Path.home() / '.journal.json'

copy(str(journal_path), str(journal_path.with_suffix('.bkp')))

journal = json.loads(journal_path.read_text())
new_journal = deepcopy(journal)

for day in journal['days']:
    new_journal['days'][day]['entries'] = journal['days'][day]['entries'][0]

journal_path.write_text(json.dumps(new_journal))