I have tested the bug extensively qnd i have tested and searched for hundreds of hours since this bug was introduced with the 1.3 patch and I've found no solution or work around: something worth noting is the plant respawns seems to get worse the longer you put into a save. At first the plants will grow back but erratically so, they will come back at odd times some areas they will be back after the two week span, in other areas it will be 30 plus days. Then some plants will be gone in areas you have not been to, then after you rake up more time with a single character the less come back.

I created a new 1.6 character to test this and the enemy respawns and the enemy respawns have not been fully addressed with 1.6 the wildlife you fight in the wilderness does not respawn at all, same thing as with the plants they will at first but after a while they will not spawn.

1.3 broke the respawns and nothing can fix it except a proper patch.