Evaluate ImportJSON() custom function less often

Hello I am using this importJSON script: https://github.com/bradjasper/ImportJSON/blob/master/ImportJSON.gs

Screenshot of my sheet: https://puu.sh/IWNt6/5d8a15138d.png

I make multiple calls in cells and I am reaching max quotas limit very often. Therefore I would like to add a timer to update all cells every 1 hour, instead of automatic updates.Any ideas how can I do it? I've tried to add trigger (createTimeDrivenTriggers) but it doesn't work since it's custom function (cell function).

Thank you