Refreshing of data stored by memristors

An actuating unit, for a memory that includes at least one memory cell in which one of a plurality of discrete storable values is encodable as an electrical resistance value of a memristor, includes: a measuring device configured to measure the resistance value of the memristor; a discretizer configured to allocate to the measured resistance value one of the plurality of discrete storable values as the read value; a comparator unit configured to ascertain the difference between the nominal resistance value of the memristor that corresponds to the read value and the measured resistance value of the memristor; and a driver configured to apply, to the memristor on the basis of the ascertained difference, a current-time profile that drives the actual resistance value of the memristor in the direction of the nominal resistance value that corresponds to the read value, so that the memory cell is refreshed.