One of the things I like to do in RPGs is to look for healing methods that are outside the norm. Here are 2 for the second dark sun game, both of which involve 6th level preserver spells and the Lend Health power, but no divine magic.

1. Tenser's Transformation

Tenser's Transformation, when cast, doubles your current HP, but disables your spellcasting. Canceling the Berserk effect will restore your spellcasting, but get rid of HP above your maximum. However, this spell does not prevent psionics use. Hence, you can heal with the following strategy:
a. Heal your Preserver (I recommend dual classing from Gladiator for more HP) with Lend Health
b. Cast Tenser's Transformation for more HP
c. Have the Preserver use Lend Health to use that extra HP while you still have it to heal others
d. If that's not enough healing, cancel the Berserk effect and repeat these steps

2. Reincarnate

For this setup, you just need a character with high HP and Lend Health, who I assume will be a Half-Giant (at least until after reaching level 9). Thing is, Reincarnate restores full HP to the revived character and doesn't have any irreversible effects (unless cast on a human, but that's another story and may work to your advantage). So, the strategy is as follows:
a. Let your Half-Giant heal the rest of the party with Lend Health.
b. Allow the Half-Giant to die on purpose. (You can use area attack spells for this purpose.)
c. Reincarnate the Half-Giant. HP you already gained from leveling will not be lost, and your stats don't change. On the other hand, this character has now been fully healed, and this spell can even be cast in the middle of battle.
d. You now have more HP for using Lend Health. Repeat if it's not enough.