  Charmonium production at heavy-ion colliders is considered within the
comovers interaction model. The formalism is extended by including possible
secondary J/psi production through recombination and an estimate of
recombination effects is made with no free parameters involved. The comovers
interaction model also includes a comprehensive treatment of initial-state
nuclear effects, which are discussed in the context of such high energies. With
these tools, the model properly describes the centrality and the rapidity
dependence of experimental data at RHIC energy, $\sqrt{s}$ = 200 GeV, for both
Au+Au and Cu+Cu collisions. Predictions for LHC, $\sqrt{s}$ = 5.5 TeV, are
presented and the assumptions and extrapolations involved are discussed.
