Whenever you restart the jar file, the upgrades are available again.
But what you see is about what you get. No scaling of abilities, or real increase of cost, or newer items other than the 4.
Take your time. Cute little game but needs a lot more growth options. Heroclicker and other games go by percentages that they grow by, as well as being able to purchase 1, 10, 100, 1000, and max. Estimating the doubling cost of an item by percentage is to take 70 and divide against it. So say you do 10% growth, you would go about 7 rounds to double. Starting at 100 to 110, 121,133,146,161,177,194, etc.
Other things you can add for it is AI programs/helpers, improved algorithms, connecting other systems, networks, and get silly with virtual machines and silly things like virtual abacuses.
Oh right, also make option for language?