OK here's a thought that works.
Jane is very close to her second KL, which means resetting it kind of gives her a free pass, which isn't really right. So, I'm going to set the Cap at being 2 Levels (ONLY if you have not reached a Level already), and 1 Level per enemy encounterance thereafter.
So in this case, Jane's gonna gain KP until she reaches KL 2, then after that she could only gain one level per enemy group spawn.
In the event that the plant trap does have to let her go due to birthing, Jane could either be attacked and raped more by her baby, the mother, or even another enemy, just to keep her out of the fight and not able to attack, but she wouldn't gain KP.
Same would go for any other scenarios.
However, lets say you make it out of the first encounter (or any) with one level of corruption already. Well, then you'd only be able to gain one level per encounter from that point on. This allows things to work out well enough I think.
From the perspective of, "why does it mean you can gain 2 the first time if you don't already have 1?"
Well, to answer that we can say that the enemies jobs are to hit at LEAST 30,000 KP from one encounter, or a KL, whichever takes them to the cap of a level. In this case, KL 1 is 15,000 to hit, and KL 2 is 30,000 total to hit, so 30,000 KP would be the threshold. However, any additional KP gained on the attack that reaches the KL mark WILL stand. So for example if you are raped and the attack brings you to 30,052 KP, you will keep the extra 52 KP, but not gain ANY on any ensuing attack in that enemy spawn.
Does this make sense at all?