The cogeneration systems of traditional sugar mills are energy inefficient due to the initial design to get rid of surplus bagasse, the disposal of which was a challenge. Recently, bagasse has gained research interest as a cheap raw material in the emerging bioeconomy. Therefore, sugar mill cogeneration systems need to be operated more efficiently to make bagasse available for valorisation in biorefineries rather than burn it inefficiently for energy. The high cost of replacement with more energy-efficient technologies versus the minimal improvement obtained from affordable retrofits presents a trade-off that needs to be explored further. This work presents the exergy and exergoeconomic analyses of an existing low-efficiency medium-pressure cogeneration system (scenario A), an organic Rankine cycle (ORC) retrofit to the existing system (scenario B), a replacement high-pressure cogeneration system that produces extra electricity (scenario C) and a replacement high-pressure cogeneration system with a let-down valve (scenario D), to determine these trade-offs and decide on the most cost-effective way to improve energy efficiency in a sugar mill cogeneration system. The analyses are based on Aspen Plus simulations of the systems. All three improvement technologies enhanced the exergy efficiency of the base cogeneration system (21.36 %). Scenario C has the highest exergy efficiency of 23.92 % followed by scenarios B and D with 22.07 and 21.36 %, respectively. Scenario B reduced the cost per unit exergy of product from 14.79 to 14.56 US$/GJ, while scenarios C and D increased it to 19.19 and 21.83 US$/GJ, respectively. Holistically, scenario D showed the most cost-effectiveness with exergoeconomic factor of 0.386, even though it still requires optimization to further reduce its irreversibility. This paper insight for decision-making on the implementation of energy efficiency improvement measures in sugar mill cogeneration systems that can be applied in other process plants.