The Foxes boss knows they cannot afford to slip into relegation trouble just six months after winning the league.
Ranieri uses the phrase 'dilly ding, dilly dong' to keep his players focused in training and bought the Foxes squad small bells for Christmas last year during their shock title-winning campaign.
But now with the champions just two points above the bottom three ahead of Saturday's visit of Middlesbrough the Italian said he now needs a bigger bell - like the one at the Vatican - to help his side.
He said: "Sometimes I say 'dilly ding, dilly dong'. I have to get not a little bell, I have to ring a big bell - St Peter's bell I have to ring! Or Big Ben - we will all go to London!
"Look, I have to look at everything. Last season I always looked behind me and for this reason I always said '40 points, 40 points, 40 points' and I started this season saying '40 points'.
"A lot of people were laughing but I knew what could happen. It is normal what happened this year with Leicester. Now we have to react and focus on the Premier League."