I used a goto

function Run()
    GameObjects = {}
    CIRCLE = 1
    RECTANGLE = 2
    io.stdout:setvbuf"no"
    local ObjectsThatDidntMakeIt,
          OriginalLengthOfPotentialObjects,
          FinalLengthOfPotentialObjectsIgnoringNils,
          TotalFailedAssigns;
    local t = os.clock()
    math.randomseed(os.time())
    do
        local rand = math.random
        local UX, UY;
        local i = 1;
        local potential_objects = {}
        for x=256,1,-1 do
            for y=256,1,-1 do
                potential_objects[i] = {x, y, CIRCLE, 10}
                -- x, y, shape, radius
                i = i + 1;
            end
        end
        local len = #potential_objects
        local finallen = len
        local failedAssignments = 0
        for i = 1, 50000 do
            ::redo::
            local ind = rand(len)
            if not potential_objects[ind] then
                failedAssignments = failedAssignments + 1
                goto redo
            end
            GameObjects[i] = potential_objects[ind]
            potential_objects[ind] = nil;
            finallen = finallen - 1
        end
        ObjectsThatDidntMakeIt = potential_objects
        OriginalLengthOfPotentialObjects = len
        FinalLengthOfPotentialObjectsIgnoringNils = finallen
        TotalFailedAssigns = failedAssignments
    end


    print( "Creating " ..
        #GameObjects ..
        " GameObjects. Time Elapsed: " ..
        (os.clock() - t) ..
        " seconds")
    print("Potential Objects started: ".. OriginalLengthOfPotentialObjects)
    print( "Potential Objects remaining: " .. FinalLengthOfPotentialObjectsIgnoringNils)
    print ("Total Failed Assignments from Potential Objects to Game Objects: ".. TotalFailedAssigns)

end

function love.keypressed(key)
    if key=="r" then
        Run()
    end
end