Improving a product, who do I ask for help?

An industrial designer should be able to help you creating a more visually impactful design. While you are investing in that work stream and new tooling an industrial designer can also help you improve the function. Ideally, to avoid commoditization, it helps if you are differentiated on three fronts: function, aesthetic, and brand. If you hire the right designer, they will be able to help on all three. I haven’t seen your product but I recommend considering function and brand in the same project so that the final product is differentiated, holistically thought through, and authentic.

Depending on your manufacturing partner’s capability and the complexity of the product you may also need a mechanical engineer and/or a sourcing developer to help get the new design ready for the factor and act as a day to day point of contact with the factory in the development process… These also might be the same person.