Prestige

Prestige will reset your factory so you play it from the beginning, but it will allow you to permanently upgrade it and it will have a much higher multiplier which means you will earn a lot more money when upgrading the factory again.

Each time you Prestige a factory, you will get an even higher multiplier and more upgrades.

To Prestige a factory, you first need to have 1.5ac in the Cash for that factory. You need to spend some Cash to Prestige, and the cost is displayed on the Prestige pop-up each time.  

When you Prestige, you will keep all of your upgrades, plus your Super Cash and other factories. You will lose your workstations, levels and the rest of your Cash.

Additionally, depending on your net worth, you will receive a certain amount of stars for Prestige. These stars can be traded in for trophies, which are permanent upgrades to your factory. These trophies can then also be upgraded with stars to provide even better boosts!