Let baby sleep?

My baby loves her sleep! I'm not complaining at all! I've been pretty good about getting her on a schedule of eating every 4 hours or sometimes sooner if she wakes up and is hungry. But when she's sleepjng, she'll want to sleep through her every 4 hour feeding. 
Should I wake her up to feed her, or let her sleep and just feed her when she wakes up? 
I hate to let her go more than 4 hours without eating. 
Btw, she eats about 2oz. Every 4 hours