Is she having any difficulties - labored breathing, not laying egg, off food/water, crop issues, difficulty walking, etc.?
Likely she's starting show a bit of fluid in the abdomen, possibly the beginning of reproductive problems to come. Cancer, EYP, Internal Laying, Salpingitis, etc. are all common conditions seen in laying hens. Sometimes as a condition progresses, their abdomen can become distended with fluid, tumors or material.
IF she starts to have some problems, then you can offer supportive care like draining fluid (if there's any), making sure they are eating/drinking, keeping parasites under control, etc.
Draining, medications, etc. are not cures, but are part of supportive care.
Since you report she's acting normal, then I'd just monitor her.