  Charmonium production in heavy-ion collisions is investigated within a
kinetic theory framework incorporating in-medium properties of open- and
hidden-charm states in line with recent QCD lattice calculations. A
continuously decreasing open-charm threshold across the phase boundary of
hadronic and quark-gluon matter is found to have important implications for the
equilibrium abundance of charmonium states. The survival of $J/\psi$ resonance
states above the transition temperature enables their recreation also in the
Quark-Gluon Plasma. Including effects of chemical and thermal off-equilibrium,
we compare our model results to available experimental data at CERN-SPS and
BNL-RHIC energies. In particular, earlier found discrepancies in the
$\psi'/\psi$ ratio can be resolved.
