When you load an existing project (e.g. "A New Hope"), it will open on a blank editor where you can start making a new chip. From what I understand, you want to continue editing the chip you were working on before closing. To do this, once you have loaded the project, go to Menu > Library. From the library, you can select the chip you were working on, and then press the Edit button to open it.
Maybe it would be a better default behaviour to open the chip you were working on last, I'll think about changing it. I hope that helps for now!