How would Shakespeare say “give yourself a bell?”
If we were to imagine how Shakespeare might express the sentiment of this phrase using language and expressions from his own time, he might say something like:

Pr'ythee, sound thyself a knell, and call to mind thy duty.

This would be a somewhat poetic way of saying remind yourself of what you need to do. The phrase sound thyself a knell could be interpreted as meaning ring a warning bell for yourself or make yourself aware of the seriousness of the situation.
Thank you, that's very helpful!