  $\epsilon$ Eridani is a highly active young K2 star with an activity cycle of
about three years established using Ca II H & K line index measurements
(S_MWO). This relatively short cycle has been demonstrated to be consistent
with X-ray and magnetic flux measurements. Recent work suggested a change in
the cyclic behaviour. Here we report new X-ray flux and S_MWO measurements and
also include S_MWO measurements from the historical Mount Wilson program. This
results in an observational time baseline of over 50 years for the S_MWO data
and of over 7 years in X-rays. Moreover, we include Ca II infrared triplet
(IRT) index measurements (S_IRT) from 2013-2022 in our study. With the extended
X-ray data set, we can now detect the short cycle for the first time using a
periodogram analysis. Near-simultaneous S_MWO data and X-ray fluxes, which are
offset by 20 days at most, are moderately strongly correlated when only the
lowest activity state (concerning short-term variability) is considered in both
diagnostics. In the S_MWO data, we find strong evidence for a much longer cycle
of about 34 years and an 11-year cycle instead of the formerly proposed
$12$-year cycle in addition to the known 3-year cycle. The superposition of the
three periods naturally explains the recent drop in S_MWO measurements. The two
shorter cycles are also detected in the S_IRT data, although the activity
cycles exhibit lower amplitudes in the S_IRT than in the S_MWO data. Finally,
the rotation period of $\epsilon$Eri can be found more frequently in the S_MWO
as well as in the S_IRT data for times near the minimum of the long cycle. This
may be explained by a scenario in which the filling factor for magnetically
active regions near cycle maximum is too high to allow for notable short-term
variations.
