Other than mana feed, there's nothing to actively restore your minion's mana. Things to watch for, however, are making sure that your pet gets buffed when possible for more mana (pally: Blessing of Wisdom, disc priest: Divine Spirit). Also, turn off her other abilities if you need to conserve succy mana for seduce. Lash of pain isn't necessary for the time you send her in to dps once the group picks up your target... just let her auto-attack.