I’ve read that it is good to have good water with added potassium and bicarbonate of soda. Then bone broth then gradually introducing foods. Avoiding sugary / starchy foods as they can mess up electrolyte balance.
After 12 days (amazing BTW) would proceed cautiously and do a bit more personal research and listen to more experienced DF folks.
Also - disclaimer - I’ve not gone anywhere near that deep and am just sharing things I remember from reading
https://i.imgur.com/RtgZNxn.png
Thats my guess I’m trying to work on the keto refeed myself. You could mess around with it and replace the salmon with nuts, red cabbage soup with something else like roasted cauliflowers, but make sure you use a meal planner like eatthismuch.com or similiar to keep track