My house is on a slab in metro Atlanta. The water supply comes in on
the left side of the house, runs under the house to the right side
where the water heater is, then the hot water goes back to the left
side, where the powder room is downstairs. Two baths upstairs above
it. And the kitchen sink in the middle.

I had a slab leak repaired in the powder room (hot water) about 10-12
years ago.

I had another repaired right under where the hot water from the heater
goes under the slab in the utility room (actually, it was probably a
foot or so beyond the wall in the den, but the plumber managed to fix
it.).

Now, 2 months later, another leak. I'm "hoping" it is the same spot
the plumber fixed last time.
I stuck a Q-tip down along the pipe through the concrete, and it came
out a little damp, though not wet.

I am considering long term alternatives, such as rerouting the hot
water return up the attic and downstairs. (maybe I should do cold
water while I'm at it)

1) Has anyone had experience with this kind of problem?

2) Is it safe to do this through the attic, that is, is there a
potential for freezing, or would proper insulation or using that
plastic pipe (PEX???) prevent it?

3) Any ideas on the reasonable cost range?

4) Would this be "code" in Cobb County, GA?

Thanks