Extending a spells duration

[Atalius]

Is there any way to extend a spells duration besides the Imperial Bloodlines Extended Spell focus power?

[HumbleGamer]

Getting a wand with increased duration.

[Atalius]

The spell would be Heightened Invisibility

[HumbleGamer]

Wand of Continuation gives you a 30 sec extra duration.

Extend spell is the exception.
If the party doesn't rest, it's pretty good as it saves a lot of spells.