How can I change the yield of pheylethanamide?

[sankeel]

Phenylethanamide is produced when a solution of pheylammonium chloride solid reacts with sodium ethanoate dissolved in water. This forms phenylamine and ethanoic acid. The phenylamine is then reacted with ethanoic acid. The product is then formed as a solid precipitate.

How can change the yield without changing the mass, concentration and temperature of the reactant? I need to develop an investigation.