Repeating a function, then executing?

Are the values of num and num2 important (ie are they used in the --code sections?) If so, what you've got is probably as short as you're going to get, unless each --code section is identical - if that's the case, do this:

local num = math.random(1, 2)
local num2 = math.random(1, 2)
--code

Since num will always be 1 or 2 and you want to do the same thing in either case, there's no point in using an 'if' statement in that case.

Do you only have two different functions (that use the value of num, but not num2)? If so, you could do this:

local num = math.random(1, 2)
if math.random(1, 2) == 1 then
	--run function 1 here referencing 'num' as needed
else
	--run function 2 here referencing 'num' as needed
end

Do you have 4 different functions? You could simplify the logic - just select your function based on a random number from 1 to 4:

local num = math.random(1, 4)
if num == 1 then
	--function1 here
elseif num == 2 then
	--function2 here
elseif num == 3 then
	--function3 here
else
	--function4 here
end

Or you could even get fancy and put your functions in a list:

--Define the list:
functions = {function1, function2, function3, function4}

--Elsewhere:
functions[math.random(1, #functions)]()

That last line selects a random number between 1 and 4 (because #functions is 4), accesses the function from the list, then runs it (that's what the ending () are for).

You could also use recursion (you did say "I'd want the function to repeat"), but you have to have an end condition to prevent an infinite loop. I wouldn't use recursion in the example you provided, but if you have a more complex scenario it might become useful. ex:

function DoSomething(attemptsLeft) --attempt to DoSomething
	if attemptsLeft < 0 then return end --prevent infinite recursion
	attemptsLeft = attemptsLeft or 5 --if attemptsLeft is not provided, it will default to 5
	--do processing here
	if somethingWentWrong then
		DoSomething(attemptsLeft - 1)
	end
	--can do more processing here if required
end