It might be the time change. Even if she's tired, if there's more light in the room, or she's seeing light in the other rooms before you take her to bed, she might be feeling like it's not bedtime yet.
Another possibility is, even if she's fed, take a look at how much she's eating in solids, and what types of solids she's eating. It might be that she's still hungry because, if solids are replacing the breastmilk or formula, and solids are not very protein-heavy (and most solids aren't, and shouldn't be, till the baby is 9 months old), then they'll go right through that little body and the baby will still be hungry.
Through the first year, solids aren't supposed to replace breastmilk or formula at all. If you think they might be filling her up and leaving less room for breastmilk or formula, taper off a bit. Feed her her meal of breastmilk or formula first, till she seems done. Then offer a few bites of her latest solids meal. No, she won't eat much or any, but she's experiencing it, squashing it, flinging it...all important learning activities, and ways to get familiar with food :)
Another possibility is that something has upset her; maybe she had a scary dream (I don't know at what age they're possible), or maybe her daily life has been upset. It could have been a grown-up fight or just a slight change in what she thought was rock-solid in her life, and the stress is making it hard for her to sleep, and hard for her to let go of her source of comfort, the two of you.
Then again, another possibility still is that she has learned how much fun it is to be awake. Our daughter seems to have started to fight sleep early on, too. She also can seem scared to be left alone. Has your daughter been waking up later, crying, and seeming afraid? If so, then, just like my daughter, she might have started to associate sleep with that frightening feeling of being alone in a dark room. What we've been doing is (well, and we have her sleep in our bed with us), we've been watching lots of movies on the laptop, using earbuds. I cuddle right up to her soon after she has fallen asleep, and my husband crawls into bed, and, as far as Eden knows, we're all just in bed sleeping together. When she wakes up hungry, I'm there to nurse her; if she tosses and turns, I put a hand on her to soothe her. The idea is, she will, after having these cozier, safer-feeling experiences when she wakes up shortly after bed-time, start to relax when it's bedtime, knowing that we'll be there if she needs us (it might just take a minute to get to her :).
If your daughter has been waking up crying in the hours after she's fallen asleep, try to beat her to it. Get a sense of when you expect her to wake next, and try to be in the room with her or nearby when she starts to rouse. Then, place a loving hand on her and/or sing her favorite lullaby or do whatever it takes to help her ease back to sleep. Make sure not to let her have any fun when she does wake up. If you speak to her, keep it brief, simple and quiet, and business only (not "do you see the bear? Isn't he a nice bear? Do you want to hold the bear?"). Be comforting, is what I mean, but don't let her start to associate late-night/post-bedtime with playtime.
I'd say, be more loving than ever, don't deny that baby comfort and reassurance, and keep a very observant eye on her, night and day, and you might pick up on something other than what any of us has suggested - or you see that something we've suggested is the cause.
Also, I've found innumerable very helpful tips in No-Cry Sleep Solution. The author is Elizabeth Pantley. She will help you with this and anything else that crops up down the road. Probably just a couple of dollars on amazon.com and so, so worth it! The way I see it is, an hour of reading her book has saved me hours of trying unsuccessful tactics to get my baby to sleep.
Good luck.
L.
