Iconic Manifestation?

[Yogibear41]

Anyway to make this spell last longer? seeing as how it has 2 durations I don't think extend or persist would work with it or do they?

4th level spell from complete champion for those who don't know it.

[Gildedragon]

Extend, I figure, makes the duration 20 min per level + 2 min per level post invocation

as for what extend does... it is either:
a day before invoking + a day following the invocation
or 1 day total, invoke it at some point and it will last the rest of the 24 hrs