If you arrive at T2 and decide to take the Keisei limited express (the Y990 train), you might give serious consideration to riding the train from T2 to T1 and re-boarding there, assuming the staff doesn't stop you. At the wrong time of day, you might not find a seat by the time the train reaches T2, I've found.

OP, remember, your JR pass is valid for 7 calendar days, if you are there for a week, your pass will be valid for the Narita Express in at least one direction.

Best to make this the direction BACK to Narita, because at the same time you are validating your JR pass, you can buy the JR N'Ex+Suica deal that effectively gives you the ride FROM Narita at half-price -- a comfortable, faster ride for only Y500 more than the much more crowded Keisei line train.