User will make Expense Claim (Type = Claim) when retire. You can insert custom link field where user can select Expense Claim he/she made for requesting Imprest.
On the submission of retirement Expense Claim, Journal Voucher will be posted. After accounting entry is posted, employee's account balance will reflect payable or receivable towards that employee.
As explained in the help document, Expense Claim form shall be used mainly for the approval of Claim and Imprest request made by Employee. You should check Employee's account balance to know payable/receivable towards that Employee.