What do you mean by “re-attach” ? Do you want something more than just re-using the entity classes (by finding fresh entities) from inside a Quartz job ?
I’ve never played with Quartz in relationship with Jspresso yet. However, a quick (and untested) idea might be to create a dedicated spring context that only contains the faceless part of the application (i.e. everything from the model up to the backend controller). This way, you should benefit from all the features you might need in an asynchronous job based on your application.
Again, this is just a starting point and if you wish to follow this direction, I will be glad to help fixing problems you might encounter.