It’s supposed to be kept full if plugged, the save files have parameters that keep track of how much cum is inside her but every sex scene end unplugs all the rotors anyway, and how much is drained is dependent on how fast you click the dialogue that switches to the next timeframe. Then after that the belly size stays dependent on the cum inside value.
Even then, every sex scene start the game cannot read those cum values and keeps resetting that number internally, making the models desynchronised with the value until the next creampie.
I have no unity engineering knowledge but this bug might be patchable if that’s the only issue, dunno who to ask about this tbh.