Can I replace a non-polarized electrolytic capacitor with a ceramic disc capacitor?
Non-polarized capacitors are supersets of polarized capacitors.  Polarization is not a issue when replacing a electrolytic with a ceramic.

In general, you can replace a polarized capacitor with a polarized or non-polarized capacitor with the same capacitance, and with a voltage rating of the original or higher.  Non-polarized capacitors may only be replaced with other non-polarized capacitors, unless you know the circuit will only ever apply voltage in one polarity.

In a few unusual cases, the circuit be relying on the electrolytic having some minimum ESR.  A ceramic won't work then because those have very low ESR.  This is unlikely, but not totally unheard of.  There have been power supplies that relied on a minimum out cap ESR for stability.  You are less likely to run into that in newer designs, now that ceramics are readily available with 10s of &micro;F capacitance.