What can I do to stop the Lollipop update prompts if I don't want to update my KitKat? I have some bad experience with my 1st gen Nexus 7, after updating to Lollipop. It made everything so slow, as to be completely useless as a device. I had to factory reset it.

My Moto G is less than a year old, and I have no desire to see it go through the same process. It is already a little slow on KitKat right now. However, the system update prompts shows up as many as 5 times within 1 continuous hour of usage. It says that it will ask me to set a time for future update prompts if I select 'No, thanks', but it doesn't.

How can I stop the update prompts from showing up all the time?
Go into your device Setting--> Apps--> All (tab)--> Open 'Motorola
Update Services' &amp; Disable it! 
If 'Disable' Option is not available
in your device then you will have to root your device and then
install SD Maid app, And grant that application root permission so
that you can freeze system apps. 
And I think so 2nd method will work 100%.