Homebrew PCBs

I etched my first board a few weeks back with HCl/H2O2 and was very happy
with the results.

I saved the etchant, since I'd only etched one small board with it, and
today tried to etch a second board.  I saw no evidence of a chemical
reaction at all.

Now, I know that H2O2 will spontaneously decompose, but it seems that the
etchant should last longer than a couple of weeks. Has anyone else had
issues with storing etchant and using it at a later date?  Is there anything
I can do to increase the shelf life of my etchant?