sorry to hear about your dad's progression. THere have been some cases where a patient has taken a tarceva "break" (went onto another chemotherapy) and then later went back to tarceva to have it work effectively again.
I also know of folks who have had avastin and tarceva and there is also the clinical trial of crizotinib but I am NOT a doctor and am not giving medical advice.
Just know that we are here for you. Please keep us updated on you and your dad.
We have an ask the experts area where lung cancer experts will answer questions for you about next line treatment and proven supplements. You may want to ask those questions there as well. http://blog.lungevity.org/ask-the-experts/
Hang in there and keep posting. I look forward to getting to know you