You just call USCIS 800- number, create a service request first based on taking longer than 90 days, if your travel date is still more than 2 weeks.
Follow up in 7 days and if they still don't approve your AP:

Call 800- number, create an expedite request (often times you may need to talk to tier 2 customer service rep) based on financial loss to individual, and emergent situation or humanitarian ground whatever applies to you. Fax a copy of your ticket and say if you can't make it, you will lose significant amount.