An existing tennis court may not need to be replaced simply because it is cracked, uneven or sinking. Resurfacing is substantially cheaper, typically coming in between $4,000 and $8,000 for a concrete court. Resurfacing can give courts a bright new color, but they can also remove low spots and even out the surface.
https://www.homeadvisor.com/cost/outdoor-living/build-or-resurface-a-tennis-court