I actually kept missing the reform rule too. I had to make a game aid, a red explosion laminated thing to lay down next to each unit that was in combat, then after combats are all done I can reform and take the markers away.
The most frustrating things I always missed were the lasting spells, I made spell cards to lay down on the table to help me remember. Then the -1 to command for casualties, I made a casualty marker a lot like the combat marker explained above (and wound markers), and confusion markers and magical item markers.
Oh AND I forget to move heroes a lot. no game aids to help me there though.
that seems like such a long list LOL