It does sound like she's telling you what her ideal awake time is, I'd just go with it. Personally with my DD I figure she'll stretch it out when she's ready. We've just hit about 2hr awake times and DD is just 5 months old, but some days after 1.5hrs she's had it, others at 2hrs she still seems raring to go! I do wind her down with quiet time though because whilst she may seem wide awake after 2hrs, the wheels fall off really quickly and she turns into monster baby The quiet time is lovely for me too ha ha

I have to remind myself that she is doing so much more with her little body and mind that somedays she just exhausts herself quicker, especially if she really goes off in the jumperoo!