  We combine all published NIR and optical photometrical observations of NGC
4151 as well as our new unpublished yet data which can be used for
determination of time delays between optical and NIR variations. Before we have
found change of time delay value for variations in K and L filters for
different states of the luminosity. Here we are considering new data for deep
minimum after the very high state of the nucleus. We conclude that dust
recovering time after the high state is for any case more then several years.
