Thanks to kevin this worked like a charm! Info provided by Kevin (use with care)
The script below will update ALL subscriptions to be out of of date and needed to be sent. Uncomment the where clauses for either daily or weekly to update only those.
You will still need to update the cron job to run more frequently of course.
SELECT * from te_EmailDigest_Subscription
set NextSendDate = dateadd(day, -1, getdate())
--WHERE Frequency = 1 /* daily */
--WHERE Frequency = 7 /* all */