"Don't hit her back!"
Yes, this sentence is a bit confusing; I'll change it to "Don't hit her in the back."
As the others have commented, yIqIpqa'Qo' would be "Don't hit [her/him/it] again!" or "Don't resume hitting [her/him/it]!" I think @kahlress62003's suggestion is good:
yInoDQo'! = "Don't retaliate!"
More fully: DuqIp[chugh/DI'] yInoDQo'! - "[If/When] she hits you, don't retaliate!"