The Active gym at Fort Regent is staying open longer than planned because the opening of a new one at Springfield has been delayed by at least three months.
Jersey's government says it will advise gym-goers of the new re-opening date as soon as one is confirmed, but it expects construction of the Springfield gym to take at least another three months.
"We apologise for the delay and thank customers for their patience."
Officials have also reiterated that there are 'no immediate plans' to close the Playzone soft play area at Fort Regent.
"It had originally been anticipated that the soft play facility would close at the same time as Fort Regent’s Active gym (which was originally expected to be in September to coincide with the previously expected re-opening of Springfield’s gym)
We are now looking for resources to keep the Playzone open while alternative facilities for soft play are considered."
The Playzone is currently advertising to recruit staff.
A ten-year plan for the transformation of Fort Regent was unveiled by the previous government in June 2021.
In February this year, the Jersey Development Company submitted plans for a lift and bridge from Snow Hill car park to improve access to the Fort.
Many sports clubs have already moved out of the centre, with the government previously saying they would all be relocated by September 2023 when a new £3m Oakfield Sports Centre is due to be ready.

Channel Islands Air Search plane "temporarily unavailable" due to registration issue
Five new laws proposed to tackle violence against women and girls
All JET staff at risk of redundancy as government caps funding
Plans submitted to replace Fort Regent roof
Jersey Post increase the number of collections from Amazon depots
Aurigny promises 'much better' Jersey-Guernsey service
Jersey bird owners now required to register their pets and livestock
Guernsey investor buys large Jersey hospitality group