I think that as things get bleaker and more helpless and it rains so hard inside the jar that it practically lashes at her and the water begins to rise and she feels like she is gonna drown - I feel that at its peak when the mason jar gets full, she can try to get to the surface and finally break free. Some people drown in their misery and self-pity, but others gather their guts and try to stay afloat, trusting that things will eventually get better and that there would eventually be opportunities to escape whatever hell they're in. Once the storm breaks and the jar is full, she can swim to one edge of the jar and try to slide down the side. Easier said than done though.