Nigel Pearson's men led courtesy of defender Liam Moore's spectacular 25th-minute strike at Deepdale, but the hosts ultimately salvaged a draw through Tom Clarke's header.
Preston, who begin their League One campaign against Notts County on August 9, beat Leicester's fellow Premier League newcomers Burnley on Tuesday and gave another good account of themselves on Saturday.
Both sides crafted chances inside the first six minutes as Ritchie De Laet denied Scott Laird with an important block, before Leicester's Gary Taylor-Fletcher saw a lobbed effort go just wide.
The visitors eventually broke the deadlock, though, and did so in style.
Taylor-Fletcher did well to pull Paul Konchesky's deep cross back to Moore and the defender fired an unstoppable volley in off the post.
The tempo of the contest slowed noticeably after the interval, with a host of changes disrupting the flow of the game.
But it was Preston who managed to find a way through as Clarke nodded in Will Hayhurst's free-kick around the hour mark.
