There is not. People have also asked for a way to make the value larger. (It's currently 1000 + turns remaining.)
If you guys want to change that, this is probably the line you are looking for:
PHP:int durationLimit = KoLCharacter.getAdventuresLeft() + 1000;
It's in the source code file MoodManager.java, line 519 as of KoLmafia version 14.1.
int durationLimit = KoLCharacter.getAdventuresLeft() + (Preferences.getInteger("maxManaBurn") > 0 ? Preferences.getInteger("maxManaBurn") : 1000)
int maxburn = Preferences.getInteger("maxManaBurn");
if (maxburn < 1) maxburn = 1000;
int durationLimit = KoLCharacter.getAdventuresLeft() + maxburn;
int durationLimit = KoLCharacter.getAdventuresLeft() + ((int maxburn = Preferences.getInteger("maxManaBurn")) > 0 ? maxburn : 1000)
Revision 8627.
I like. Now there's an answer to give to people who ask the question, but it won't clutter the interface. I like secret preferences in KoLmafia.
Perhaps we're going to need a page on the wiki to list all the hidden options so that they aren't too secretive.