Answer is:increase [Cl₂] and remove HCl from the product.
Chemical reaction: Cl₂ + CH₂Cl₂ → CHCl₃(chloroform) + HCl.
According to Le Chatelier's Principle, the position of equilibrium moves to counteract the change, the position of equilibrium will move so that the concentration of reactants decrease (Cl₂) and concentration of products of chemical reaction increase (CHCl₃) if increase concentration of reactants and decrease concentration of products.
