Limited space in ARIS Express?

While working on my current project in ARIS Express, I discovered that there's a limit for the document. I can't continue with my process model because I simply have no space left (yes, it's a complex process).

Is there any solution? Because the only way I figured out to get more space is to reduce the size of every object which is of course not an option due to the huge amount I have already imbedded in my process (or is there a way to do this automatically?).

Or is this due to ARIS Express and I need a full version of ARIS?

Thanks in advance.