I lost my hamster and I'm not sure how to get her back!?

So I have a pet hamster and recently my dad has been re-constructing our house and taking up floor boards and because our house isn't fully decorated yet there are some holes, like near the electric fireplace, in the floorboards, etc. Well recently my hamster escaped because we have this cage we needed to return because it's lid is faulty and wont shut correctly, we put books on top of it until we got were to get the problem sorted, but we didn't get around to sorting the cage out. My hamster escaped late Sunday night to around very early morning, we know this because my dad went to bed and he saw her in her cage perfectly fine around late Sunday night. So we woke up the next morning and the books fell off her cage and her lid was loose, we briefly looked around the house and couldn't find her, but because we're downstairs due to the construction on our house means that she was in the dining room and we have an arch going through our dining room to our living room and the living room is a door away from the kitchen. We couldn't find her and because there's so many holes in the room we gave up for a while because we figured she'd be asleep as it was morning. So when I came home from school we waited until night and then we considered the fact that she could have climbed the stairs, although I couldn't of imagined her to do so, but she was able to. My mum said it would have taken her a long time to climb the stairs, but then she did have all night so that was a fact we might like to consider. We did hear a series of sounds that night when we were looking for her, and in the dining room we found no holes that she could squeeze through and she wasn't stuck in any of our recliners as we went through them and looked under them, not in any of our drawers, not behind the bookcases or not inside the kitchen as the door was closed and she wouldn't have been able to fit through. So the only main place she could have gone was the gap under the fireplace, which has many boards for her to climb, but has many stone walls around it, I never thought she would be able to climb up there but we looked up the wall by using my brothers phone with the torch to record up there and she was nowhere to be seen, however it did go right up to the top ceiling of our house so we did consider that she could have been up there and that was the most obvious place to look. Only recently have I gone upstairs and seen that the main places she could have gone was my brothers room, which door he usually keeps open slightly, my room but its all boarded up and my dad has sorted the holes out in that room, or the bathroom, which floorboards are all up with lots of holes, but the holes only lead under the floorboards so she'd be fine underneath and there's so many places to look in the bathroom, so there's two main places she would have gone, up the fireplace wall, which is completely safe, or under the floorboards upstairs. How can I find her? It really upsets me that I don't know where she is and for all I know she could be gone. We also found a hamster dropping near the coffee table which is near the fireplace, so she might have been up there.. please help me, and if you spent your time reading this I really do appreciate it! Thank-you so much if you can help me and it actually works, I can't spare the fact that she could be dead and I don't know about it, I'd rather her die in her own home, thank-you!