I think 2hr may be a bit much for her. I found OT naps much easier to resettle though, provided I got in there really quickly or went in at 25min and held my hand on DS if he stirred. Once they're worked up, its harder to resettle.
When you say the first nap was UT, why do you say that?
I don't think you can just jump A time to 2hr and stick to it without taking into account her nap length - you'll end up with a very OT baby and that blind clock-following is something Tracy was very much against.
For shortening A times following short naps, try reducing the next A time by half the missed sleep, so if your A time is 1:50 (probably reasonable given the UT nap at 1:45 this morning and in the last few days) and the nap is 1:10, then reduce next A time to 1:40, if you have an OT nap of 30min, reduce next A time by 30min. Its a general rule, doesn't work for all babies, or even most babies but it is the 'average' and gives you something to work from.
I think the easiest way to get the right A time is to watch the clock until ~10min before nap time and then watch baby for sleepy cues. If no cues in 15-20min though, PD for nap anyway and be prepared to resettle an OT waking ~30min into the nap.