I don't know what age your daughter is, but at some point maybe it could help to have her consider the following: do you want to be the best you can be, or do you just want to win a lot? It's a legitimate question.
Where I'm from, there's a lot of different levels of education (academically). Growing up, my mother always warned me that at some point they'd put me in a level where I wouldn't be at the top of my class anymore, and that's ok: it means I've found the level that is challenging for me.
Apologies if the anekdote is a bit odd, but here's my point:
If you're always the best, I think sometimes that just means you're at the wrong level. If the competiton is tough, and you're not always placing, that means you're challenging yourself. That is something you can be proud of. If all your daughter wants is to place and to medal, then she could consider one of the gyms that holds their gymnasts back too much. But I think there is a way of looking at this as: "Wow, these girls are amazing and I'm starting to keep up with them. Just think how good I'll be next time when I get even better".
Of course, there's a balance, you need to be at a level that is fun and safe even if it's challenging.
I think it's perfectly okay to be dissapointed, learning to handle dissapointment is a part of life and it's okay to be sad about something. That being said, I agree with the others; celebrate, make it clear that you're proud of her efforts and improvements, and maybe talk about how she feels about everything and what her motivations are when she's up to it.
Good luck with everything
PS. Sorry if my post is a bit convoluted, I hope I frased things in a kind and helpful way.