If you are looking for a larger degree of magnification, reverse mounting the lens might be a good option.
If you are using a lens with floating elements (or even without) diopters or close-up filters can help as it will change infinity focus to something else. +1 diopter changes infinity focus to 1m, +2 to 0.5m, +3 to 0.3m, and so on. These lenses have a bad rap, but they have some real advantages like compensating for exposure and reducing the impact of diffraction (if you are at f/11, but have a larger bellows extension, your effective aperture can be much smaller which impacts both).