Since a solar sail needs to have a huge area to capture enough energy from the Sun, but also be thin to make it easier to move, its design and materials are a big engineering challenge.
Is it possible to reduce its size, but instead increase the amount of energy it receives?
Increasing the amount of energy could be done with a constellation of mirrors+lenses in orbit to deflect the light from the Sun to the sail. These network of mirrors could be used for different sails (reusable), and making the sails easier to build, as some of the complexity is translated to the mirrors. Even the mirrors could have long lifetime, given that they should be easier to maintain than a sail that is travelling. Even lasers could be used to propel the sail. Specially as the energy received from the Sun is decreased as the sail travels.
Sorry for the lack of details around this idea, I'm wondering about the constraints to implement something like this, like restrictions in the amount of energy that can be transmitted from the mirrors to the sail, or collected by the mirrors, or economic costs of such a satellite constellation.