Your profile says she isn’t spayed, if she still isn’t, spaying can really help the smell.
What kind of litter do you use? Wood pellets I believe are regarded as the best for odor control. If that’s not an option, scooping out wet litter every day will make a difference.
While I was working crazy around christmas (I’m in retail lol) I had to go a little longer between litter box changes. Some things I did–I hid dryer sheets in their bedding (ONLY do this if you KNOW she will not be able to get to the dryer sheet as some rabbits WILL EAT THEM) and I used a plugin to help mask the smell. I also put apple cider vinegar in their water–some people swear by this, and I really think it works. Just mix a spoonfull or so of apple cider vinegar in with her water. But make sure it doesn’t cause her to stop drinking it. My buns didn’t care lol.
Make sure she hasn’t peed on her blankets or the floor or anything, sometimes they sneak it in and that can cause some bad smells.