I had a Genie lamp that I had already made 2 wishes from when I traveled to the future. While there I click on the lamp and noticed that instead of an option to summon the genie I had the option to clean the lamp again. So I cleaned the lamp and got a new genie and had three wishes available again.
To see what would happen I stayed in the future long enough to make 2 wishes then went back home to the past. After arriving back home I again had the option to clean the lamp and got another new genie with three more wishes.
I started a new game to see if maybe it was a bug with that one game and had the same results. The lamp gets reset when traveling to and from the future.
As long as you don't make the third wish or free the genie and lose the lamp you can have unlimited wishes.
I wasn't sure of the best place to put this sense it involves 2 expansions so I picked here. If it would be better some where else I'm sure one of the mods will move it for me.