I currently have an iPhone 5 running 6.1 and am having it replaced under warranty due to a screen problem next week.

The new phone I will get will probably have 6.1.4 on it, and I was wondering if there was any way of downgrading so I could jailbreak again?

I don't have an SHSH blobs as I've never really understood how they work (if anyone can explain this to me I'd appreciate it).