disconnect it from the network
promote the guy that said 5 years ago that you need starting to save money for replacement
fire the guy who blocked that
start saving the money for the replacement
You think that I'm starting to save money for my new car only after my old car breaks completely?
Hi and welcome to the government. In general, we don't get to save money. Each year we get a budget, at the end of the year they gather it all up in the national surplus/deficit and we start over at zero with a new budget. Without acts of the relevant national assembly to create permanent funds what you are suggesting is illegal. Even transferring funds from one year's budget to the next because the project as suffered a delay is bureaucratic and risky - anyone higher up might decide to ax the project to reach their budget. This is why so many public offices go on a spending spree at the end of the year, if you don't use it the funds will be gone and on top of that next year's budget will probably be cut since clearly you don't need that much money.
The goal is of course to keep oversight, if the government's money went into thousands of small slush funds kept by various departments for various reasons there'd probably be a lot of hoarding and questionable re-purposing of funds and no real guarantee that they'd actually cover the major investments needed anyway. Instead the government believes they are so big that the year to year variations on the total is negligible, every year so many buildings must be renovated, equipment replaced, maintenance performed in all branches of government that all report in their needs and all get their share in the national budget. So in theory you'd put in a request for replacement funds when it needs replacing, it gets rolled up from your department, your hospital to the national healthcare service to the national budget, and funds are awarded down the same line.
Of course there are far more wishes than money so in reality each level down the chain only gets so much money and has to prioritize and more likely than not somewhere along the line your request for replacement will fail to make the cut. And that's where you are in the IT department, it's not going to be replaced and you may try again next year but that's not your call. You are just stuck trying to make the best of it and hopefully not be the cause of any major outages or putting patients at risk. I guess if shit hits the fan you can always say "I told you so", but you'll be the one taking most of the shit anyway. It's the way governments do business, if you want to make it different you'd have to redo the whole system not trying to find one scapegoat.