Hmmm...

The game can't reset, because it is NOT on your computer, and you cannot see it.

The only thing you can see is what your web browser and Adobe Flash client is showing to you.

And Flash is notoriously unstable, temperametal, bugged and prone to hang or crash, meaning you may be clicking in the void and your click requests may not have been transmitted to the server to be processed.

So in the end, the only thing that resets is your own Internet browser, not the game. And what you can see when coming back is the state your city was when you stopped communicating with the server because Adobe Flash crashed one more time.

If you want better stability, please use a more stable and Flash friendly web browser.

The best one is Google Chrome.

People now say Microsoft Edge behaves satisfactorily as well.

Avoid using Firefox like plague : why excellent otherwise, it can't handle Flash more than half an hour before crashing like a fresh dung.