Notifications to be sent till task is completed

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We would like to see if we can setup notifications be sent till the approver approves the notification / task is completed. When the employee submit the expenses,manager will get reminder notification for 3 times & then there is no followups.  During year end,staff has to withdraw & resubmit the expenses since managers lost track of approval notifications(we prefer mail approvals).Is there any way that we can setup reminders to be sent till the task is completed

Current setup as such Frequency 3 & reminder 2days(after assignment)

FYI- we dont have any expiry settings