  Context: Extended circumstellar emission has been detected within a few 100
milli-arcsec around > 10% of nearby main sequence stars using near-infrared
interferometry. Follow-up observations using other techniques, should they
yield similar results or non-detections, can provide strong constraints on the
origin of the emission. They can also reveal the variability of the phenomenon.
  Aims: We aim to demonstrate the persistence of the phenomenon over time
scales of a few years and to search for variability of our previously detected
excesses.
  Methods: Using VLTI/PIONIER in H band we have carried out multi-epoch
observations of the stars for which a near-infrared excess was previously
detected with the same observing technique and instrument. The detection rates
and distribution of the excesses from our original survey and the follow-up
observations are compared statistically. A search for variability of the
excesses in our time series is carried out based on the level of the broadband
excesses.
  Results: In 12 of 16 follow-up observations, an excess is re-detected with a
significance of > 2 sigma, and in 7 of 16 follow-up observations significant
excess (> 3 sigma) has been re-detected. We statistically demonstrate with very
high confidence that the phenomenon persists for the majority of the systems.
We also present the first detection of potential variability in two sources.
  Conclusions: We conclude that the phenomenon responsible for the excesses
persists over time scales of a few years for the majority of the systems.
However, we also find that variability intrinsic to a target can cause it to
have no significant excess at the time of a specific observation.
