How do I fix a file that crashes Numbers?
Your best bet is to report a bug in Apple Numbers using this form:

http://www.apple.com/feedback/numbers.html

Be sure to include the exact version of Numbers you're running as well as the complete crash log, or at least this part of the stack trace:

  Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   com.apple.iWork.Numbers         0x000000010e4ccbca 0x10d523000 + 16423882
1   com.apple.iWork.Numbers         0x000000010e3e11ab 0x10d523000 + 15458731
2   com.apple.iWork.Numbers         0x000000010e3e1061 0x10d523000 + 15458401
3   com.apple.iWork.Numbers         0x000000010e3ca64c 0x10d523000 + 15365708
4   com.apple.iWork.Numbers         0x000000010dd6a9c7 0x10d523000 + 8681927
5   com.apple.iWork.Numbers         0x000000010e3ca5bc 0x10d523000 + 15365564
6   com.apple.iWork.Numbers         0x000000010dc0124d 0x10d523000 + 7201357
7   com.apple.iWork.Numbers         0x000000010dbebd2b 0x10d523000 + 7114027
8   com.apple.iWork.Numbers         0x000000010d5327ec 0x10d523000 + 63468


Apple will have the debug symbols that tells them, which specific functions are involved in the crash.

Then you have to sit tight and wait until a new version of Numbers comes out where the bug is hopefully fixed. It is entirely likely that the bug won't be fixed, so don't get your hopes up too high.

Fixing the file yourself requires intimate knowledge of the Numbers file format, as it sounds like you might have a valid file that crashes Numbers - and not a corrupted file. It is very hard to give advice on how to fix the file yourself when you're not sharing the file in question.