How do you know when to start adding foods back in after the reseeding phase, and which foods to add?

It's important to carry forward the practices of better nutrition— more vegetables, avoidance of pesticides (commercially-sprayed food), and genetically-modified food (commercial corn, soy, etc.), because pesticides and GM foods insult the gut-microbiome. The continued use of small amounts of fermented vegetables establishes the benefits of the transient lactobacillus species. Inclusion of fiber encourages probiotic species to proliferate and be dominant.