Spiritual Weapon and ability bonuses / damage

[Tamago]

If a Cleric is using a Spiritual Weapon spell (which allows him to add his Wisdom modifier to the attack roll), does the spell's attack change if the character's Wisdom changes?

For example, Claire the 3rd-level Cleric has a Wisdom of 14. She casts "Spiritual Weapon", and the spell attacks at +4 (+2 BAB, +2 WIS). The next round, she casts Owl's Wisdom. Does the Spiritual Weapon still attack at +4 (using her Wisdom at the time of casting) or +6 (using her now-increased Wisdom of 18)?

Conversely, if she were to take Wisdom damage, would the spell's effectiveness decrease?

Thanks for your advice!

[Lyrax]

I think so. The alternative sounds like more work, to me.