  We study the effect of thermal charm production on charmonium regeneration in
high energy nuclear collisions. By solving the kinetic equations for charm
quark and charmonium distributions in Pb+Pb collisions, we calculate the global
and differential nuclear modification factors $R_{AA}(N_{part})$ and
$R{AA}(p_t)$ for $J/\Psi$s. Due to the thermal charm production in hot medium,
the charmonium production source changes from the initially created charm
quarks at SPS, RHIC and LHC to the thermally produced charm quarks at Future
Circular Collider (FCC), and the $J/\Psi$ suppression ($R_{AA}<1$) observed so
far will be replaced by a strong enhancement ($R_{AA}>1$) at FCC at low
transverse momentum.
