It’s a really very easy process, but you have to follow it exactly. The below instructions are for a Nexus 7 tablet with Android 4.4 KitKat, but adjusting time/date settings on other Android devices will be very similar.
Lose all lives
Exit the Candy Crush app
Open your device’s Settings menu
Tap on Date & time
Unselect Automatic date & time
Tap on Set date
Change the date to at least 1 day earlier
Tap on Done
Exit the Settings app
Go back to Candy Crush
Verify you have new lives
DO NOT PLAY
Return to your Date & time settings first
Select Automatic date & time
Then go back to Candy Crush and play
If you start playing before you change the date/time back to automatic, the next time you lose all of your lives you will receive a ridiculously large countdown to your next set of lives. This amount of time will roughly equal the amount of time you set your date back.
To fix, just go back and set your date/time manually to be ahead of the countdown time, verify you have new lives in Candy Crush, set the time/date back to automatic—then play.