Well, you've cleaning out a sixteen-by-sixteen chunk area of all of it's non-renewable resources, but you've built your kingdom and city upon said region. What should you do? Try uRegen! This will cause ores to regen in a long period of time, anywhere from one minute to one full, twenty-four-hour, real-world day (in theory, it could take even longer, but this is unlikely). The change is weighted dependant of the ore's value and usefulness in the game. In general, diamond will take much longer to regenerate than coal. Through a configuration file, you can even add support for blocks from mods!
v4.1 - Fixed a small bug