Regularly investing in your leaders is the way to go if you want multiplication. Have a calendar they are all aware of. It can be quarterly if that will help. It helps them to plan other events also around it.
Our church is run on the lay system which means that everyone including the pastor has a secular vocation and does the ministry alongside. Leaders are trained from within who are taught to sacrifice their time and resources for the Kingdom work as well. There is something in our church called Work For the Lord, All Day Long!. It’s also called Sunday For Jesus. We try to give our Sundays to the building of the Kingdom. I try to meet the leaders every Sunday for extended periods of training.
Do not assume your leaders will stay. Let them know when there are meetings ahead of time. That will be your blessing and prepare for these meetings way ahead of time