The wind industry is currently facing a major challenge due to the ageing of the wind turbines that were first commissioned. Recent wind turbine designs present higher power performance and lower maintenance requirements than older wind turbines. Furthermore, most of the old wind turbines are installed in the best sites for wind resource exploitation. Under this framework, the repowering of wind farms with the replacement of the old machines by new designs is recognised as a focus area for the wind industry. This paper performs a techno-economic analysis of a real wind farm repowering experience at the Malpica wind farm, located in the Northwest of Spain. Results show the annual energy production of the repowered wind farm increases up to twofold that of the old wind farm with the same rated power. Moreover, the economic analysis reveals the project yields satisfactory profitability, even without reliance on public subsidies as currently happens in Spain. In addition, a sensitivity analysis allows us to understand the effects of the uncertainties over the lifetime of the wind farm, and how they affect the projects performance and profitability.