Homebrew PCBs

The peroxide decomposes into water and oxygen real fast, so "some"
peroxide will rejuvenate it a little, but consider that you started
with *2/3* peroxide - a little isn't going to make it as good as new.

I have an older hcl/h202 solution that I'm slowly turning into a CuCl
solution and the etch time is on the order of an hour or so, but it
does make progress.  I run the bubbler to recharge the cucl, which
evaporates some of the water, making room for more peroxide when I get
back to it.

However, I'm guessing my 3 liter tank will need at least a pound of
copper (16 12"x12" boards) to get to the "sweet spot".