Work at the Glasgow Royal Infirmary (GRI) unit was finished at the end of March. The centre had stopped carrying out IVF procedures 18 months ago after a dramatic dip in success rates.
However, women cannot be treated at the revamped facility until a government watchdog has inspected the premises and its findings are approved by the body's licencing committee.
No date has been made public for the inspection, but members of the Human Fertilisation and Embryology Authority (HFEA) will not meet to discuss the unit until early July.
Between November 2012 and the end of March this year 1300 women due to have fertility treatment at the GRI were sent to the Nuffield Hospital in Glasgow.
GRI patients will be treated at the private hospital until the new NHS unit is licenced and opened.
Jackson Carlow MSP, Scottish Conservative health spokesman, said: "This saga has been going on for too long and it is unacceptable that there is going to be a further delay before patients can access the newly refurbished clinic.
"While people will understand the need to ensure that the new clinic passes an inspection, their patience is being tested because of too much red tape.
"New clinics are there to be used, not left abandoned while officials fill in an endless variety of forms."
GRI patients were switched to the Nuffield in November 2012 after consultants found the IVF success rates had fallen from around 30% per cycle to 15% from September 1 to November 9.
An internal investigation did not establish a definite reason for the drop, but suspected that air pollution from nearby building works may have contaminated the sensitive fertilisation process during which eggs and sperm are mixed in a petri-dish. Clinical error was ruled out.
Fertility clinics must comply with the terms of a licence granted to them by the HFEA. It carries out a full inspection every four years and interim inspections every two. In July 2012 HFEA inspectors were critical of a number of issues at the unit including staff shortages.
Initially the cost of the refurbishment was estimated at around £1m and was due to take a year, but hospital bosses later increased the scale of the work to be carried out.
A spokeswoman for NHS Greater Glasgow and Clyde said: "NHSGGC's £3.5m capital works to refurbish the Assisted Conception Unit laboratory and theatre and expand the outpatient facility was completed on time at the end of March.
"The unit has now been handed back to NHSGGC for commissioning from the contractor and HFEA's period of inspection is due to begin in the next few weeks.
"This period of inspection - the length of which is determined by HFEA - is a standard process which is undertaken prior to the opening of any newly refurbished or constructed Assisted Conception Service. Once HFEA report that they are satisfied the unit meets all the necessary requirements we will open the unit and the inpatient activity will begin to transfer back to the Glasgow Royal Infirmary."
She added that arrangements were in place with the Nuffield to allow the health board to extend its contract on a month to month basis as necessary.
A spokesman for the HFEA said: "The provisional date for review by the HFEA's Licence Committee (LC) of the inspection outcome in this case is early July 2014, and therefore the inspection must be undertaken before then. No further comment on this matter will be made by the HFEA until after the LC has met."