I have abpa, currently feel fine, most recent ige was 1013. is there a point when i must take prednisone to reduce the ige?

Depends on last IgE: A sharply increased ige, infiltrates on chest x-ray and worsening asthma symptoms can indicate a flare of abpa. To know if the current ige is relevant to a flare of abpa that will require prednisone, it would be necessary to know the last total ige level. Even with minimal symptoms, it may be useful to have spirometry to assess current lung function.