The Verdict: Clear Path
You do not need to reacquire anything: the law has already made you a Canadian citizen again, back to the day you lost it. Apply for a citizenship certificate to prove it.
Until February 1977 Canada took citizenship away automatically from anyone who became a citizen elsewhere, and a later rule took it from some people born abroad who did not apply to keep it by 28. Both losses are now undone. Anyone who lost citizenship other than by formal renunciation or revocation is a citizen again, and counts as having been one throughout.
That backdating reaches your children. A child born to you after the loss was born to a Canadian parent, and there is no generational limit for anyone born before 15 December 2025, so your children and grandchildren may well be Canadian too.
For the certificate, document the loss as well as your Canadian birth or naturalisation: the foreign naturalisation record with its date, or the papers from before your 28th birthday. Once the certificate is issued you can apply for a passport. A refusal you received before December 2025 is no longer good law.