The second bath don't need to be stored, it is said to pour down the drain. But if you reuse it, I think it will work if the pH is about 11,6 to 11,8 or even 12. Today I made a try with pH 13 and less time, I still don't have results to show but I leave this two pictures of yesterday, developed with the same solution I already used twice. No signs of exhaustion,
|No color correction at scanning|
|Correction with more blue and green|
On the other hand, the bleach I am using seems to last almost forever and you only need very weak solution of it for 2-3 minutes only. Like suggested by Donal Qualls, I am using a stop bath of vinager between the second developer bath and bleach, to prevent the formation of gas of bleach reacting with sodium carbonate and hydroxide.