The one who intended to do Hajj or ‘Umrah does not have to do anything if he passed the meeqaat and forgot to enter ihraam, then he went back and entered ihraam
Question

I went for umra recently from riyadh , I put the ihram at home without making the niyat thinking that I will do it on the plane before crossing the meeqat . unfortunately I did not hear the announcement about the meeqat on the plane and was unable to do the niyat because the plane had already crossed the meeqat . I made the decision to go to Mecca , on arriving in Mecca , I took the ihram off and put regular clothes on and drove to qarin-manzil in taif . there I put the ihram again and did the niyat of umra and came back to Mecca and performed the umra . please tell me if I did it right or I have to pay the penalty and if do have to pay the penalty then what I have to do . please respond .
Praise be to Allah.Whoever passes the meeqaat without entering ihraam has to go back and enter ihraam from that point. If he got off the plane in Jeddah, then he has to take a car to the meeqaat of the people of Najd and enter ihraam from there. If he enters ihraam from Jeddah and he is intending to do Hajj or ‘Umrah, then he has to offer a sacrifice as expiation for passing the meeqaat (without entering ihraam).
Fataawa al-Shaykh ibn Jibreen 
See also similar fatwas in Kitaab Fataawa Islamiyyah, 2/202 
You did the right thing by going back to the meeqaat and entering ihraam from there.  The fact that you took off the ihraam garments does not mean that you have to offer the sacrifice, because you did not enter ihraam in the first place. Ihraam means the intention to enter the rituals, not just wearing the garments of ihraam. Based on that, what you did was correct and you do not have to offer any kafaarah (expiation), praise be to Allaah.