To readapt is to get used to a certain situation or condition again. If you move back to a remote island after a few years in a large city, you'll have to readapt to the solitary, slow-paced life.
When college graduates move back home with their parents, they have to readapt to living in their childhood homes, and sometimes to rules and expectations that didn't exist back in the dorms. And if you dig up a clump of daisies in your yard and move them to a sunnier spot, they'll need to readapt to the new soil. Readapt adds the "again" prefix re- to adapt, from the Latin adaptare, "adjust" or "fix."