  A number of pulsars are known to have profile evolution on timescales of
months, often correlated with spin-down rate changes. Here, we present the
first result from 3 years of monitoring observations from MeerKAT as part of
the Thousand Pulsar Array programme. This programme obtains high-fidelity pulse
profiles for $\sim$ 500 pulsars, which enabled the detection of subtle changes
in seven sources not previously known to exhibit long-term profile evolution. A
2D Gaussian convolution is used to highlight correlated emission variability in
both the pulse phase and observing epoch direction. Simulations show that for
one additional source the observed profile variability is likely to originate
from stochastic single-pulse shape variability (jitter). We find that it is
common for long-term profile variability to be associated with changes in
polarization fractions, but not with polarisation position angle (PA) changes.
PA changes are expected if emission height changes or precession is responsible
for the profile variability. PSR J1741$-$3927 is the only pulsar in our sample
that shows correlated PA variability, and this is associated with orthogonal
polarization mode activity. For the six %the rest, without correlated PA
variability, other pulsars limits on possible emission height changes and
impact angle changes are derived. These limits are consistent with the small
changes in the total intensity profile shape. None of the sources show
detectable spin-down variability correlated with the emission changes, which
are thought to be driven by magnetospheric current fluctuations. Therefore the
absence of correlated spin-down rate variability allows upper limits to be
placed on changes in the magnetospheric charge density.
