You can chose one island to be your Home Island in Portal Knights. This allows you to travel to this island very fast, and it also prevents it from being altered even when you regenerate your universe. It's very simple to change your home island, and you can do it whenever you feel like it.
To change your Home Island, go to the island travel screen and click once on the island you want to set as home. This opens up a menu with the enemies and drops on the island, as well as the options to "Travel" there, or "Set it as Home". As you can imagine, the latter option sets the island as your Home Island, and it will stay that way until you change it for another island.