periodically

to make something more modern or up-to-date at regular intervals

to formally assess something at regular intervals, with the possibility of making changes

to examine something at regular intervals to ensure it is correct or safe

to carry out a test at regular intervals to assess quality or performance

to watch and check a situation carefully over a period of time at regular intervals

to look at something carefully at regular intervals

to re-examine and make alterations to something (like a document or plan) at regular intervals

to make something like a contract or license valid again at regular intervals

to come or go back to a place at regular intervals

to stop the continuous progress of an activity or process from time to time

to break out suddenly and dramatically from time to time, like a volcano or conflict