The building and operation of the funicular has run to £26.75m
Public agency Highlands and Islands Enterprise (HIE) is to spend up to £4m over the next three to four years on the Cairngorm's funicular railway.
HIE said the investment would bring the site up to a standard that would attract a new operator from the private sector.
HIE has also proposed charging at a car park serving the railway.
The agency took the railway over last year. A review of its spending on the site is being considered by MSPs.
The agency has already provided £19.42m of more than £26m spent on the railway so far.
Douglas Yule, director of operations at HIE, said the new money was needed for maintenance and to ensure the site compiled with health and safety legislation.
He said: "As the landlord of the entire estate we do have to invest in order to protect the integrity of the asset."
However, Dave Morris, of Ramblers Association Scotland, said the running of the site should be handed into the care of another public body.
He said: "It will never make money. All the problems which we highlighted 10 years ago have now been proved to be true.
"The only solution is to remove HIE from the mountain and either have the Forestry Commission or Cairngorms National Park to take over responsibility."
HIE took over the funicular and the Cairngorm ski resort last May.
It followed agreements reached with Bank of Scotland Corporate and CairnGorm Mountain Trust on large debts owed by CairnGorm Mountain Limited (CML).
Highland Council also agreed to write off a £1m loan to CML.
The running of the mountain railway, which started operating in 2001, is expected to be put out to tender.
About 400,000 people used the car park serving the railway last year, according to HIE.
It said half those visitors used the funicular.
Meanwhile, the Scottish Parliament's audit committee is gathering evidence on the financing of the funicular following an investigation by spending watchdog Audit Scotland.