Still suggest electrolysis because salt are renewable, but here are other ineffective methods
Manganese method:
2 NaCl + 2 H2SO4 + MnO2 → Na2SO4 + MnSO4 + 2 H2O + Cl2
MnSO4 can be recycled back to MnO2, via electrolysis (you cannot avoid it)
MnSO4 + 2 H2O = MnO2 + H2SO4 + H2 (electrolysis)
Deacon process:
4HCl + O2 = 2 Cl2 + 2 H2O (RuO2-TiO2 as catalyst)
Ruthenium is very rare, though RuO2 is reusable after the reaction