are there still hidden packs if you replay a map?
Nope there isnt.
I just started a second play through, but my guess would be no. Just the 1000 and 10 standard packs for all the hex.
I do not think there should be the hidden one's for 2nd play through BUT i saw someone else mention something like every ranked season some of the rewards reset. I think this was a solid idea but i do not think it should be tied to that but once done there is a 15 to 20 day timer. When that runs out next time you start a FRESH Board you get the following missions variation of the originals :
1) 1 Standard pack for all AL Strong Holds and 1 for all NL Strong Holds = 2 free Packs
2) 2 or 3 random for 1 pack and another 2 or 3 for like 50 Stubs and 250 XP
along with the standard 1k XP and 10 pack
i have another idea but i think this idea would have to wait for next years SHOW game ..