I thought I had read this somewhere. A standard augment spell lasts till the start of your next turn. How do you extend this duration?

add 1 purple?

pay extra strain?

smae applies for utility and barrier spells.... thanks!

If the spell has "Concentration: Yes" under it then you can perform the concentration maneuver each subsequent round to maintain a spell, both Augment and Barrier do have this, but Utility doesn't, although Utility is for simple things so I imagine it isn't required generally, but if you think it is then use the same rule I guess.

Concentration is explained on page 218 in the main book.

Concentration spells last until the end of your next turn. Performing the concentrate manoeuvre extends that until the end of the following turn.