Having taken charge during the off-season, Grady and Leather have guided the Crusaders to a League 1 Cup final in their first season and will now look to build on that success next year.
On his new deal, Grady said: “I’m delighted to be signing with the club again for next year.
“Myself and Jonny [Leather] have enjoyed our first season here, and now want to improve on that next year.
“The fans have been amazing and were a big factor in me wanting to stay.
“It’s also important that Jonny has stayed as well – he does a lot of work that goes unnoticed but has played a huge part this season.
Crusaders Chairman, Ian Edwards, said: “We are delighted to have secured Mike and Jonny for another 12 months, and although we only signed the contracts after the Coventry match, we’ve been making plans for next season with them for several weeks.
“As well as making great strides in moving the squad forward Mike and Jonny have a developed a great rapport with the fans who we’re sure will be as delighted as we are with the appointments.
“We hope the supporters will get behind them and the team for the remainder of this season, and for the season ahead so that together we can all build an exciting future for North Wales Crusaders.”