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absolutely not.
under no circumstance should you upgrade a jb phone to a new version without restoring first. you'll brick your phone. just dont do it k?
 
You should restore first. If not, you will have problems installing apps again. It wont hurt your phone or anything, but it wont work that great and you will want to restore it anyway.
 
Put your phone into recovery mode, then restore, and let iTunes upgrade your phone during the restore...
 
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