We did consider adding lives, however after implementing the running mechanic we didn't find it to be necessary! Did you know about the running mechanic? I ask because a few people I know didn't realise.
We wanted to add an in-game tutorial so that people would learn about running before playing the game, currently the tutorial is on the GitHub README which is less than ideal!
Protip: Swipe / drag the chickens in the direction that they are walking to make them run!