Escalation feature in PeopleSoft Accounts Payable

Hello,

We are on PeopleSoft 9.2 ( Image#33). We have setup automatic email alerts for vouchers pending approvals using the Alert component in PeopleSoft. Below are the pages that I used to send emails to approvers based on custom query.

1. Enterprise Components>>Events & Notifications>>Alerts>>Alert Definition

2. Enterprise Components>>Events & Notifications>>Alerts>>Run Alerts

3. Enterprise Components >> Events & Notifications>> Notifications Framework>> Notifications Registry

The users are requesting an escalation feature so that if a voucher stays in the queue of an approver for a specified number of days, an email should go to the next level of hierarchy which is the supervisor informing him/her about the pending voucher. I have not seen any feature while setting up the automatic alerts and would like to get some advise if there is any way to configure that in AP along with the alerts.