Nope, as I keep saying… it’s a sealed system. If it fails after more than a few months then it’s not needing topped up it’s needing more than that.
I expect that the compressor is weak from running excessively during the summer months and it’s effectively not an economical repair.
That’s the thing with conservatories, garages and outhouses… too cold in the winter, too warm in the summer.
K.