Open Enrollment with Life Event and Unrestricted Plans

We're beginning testing for Open Enrollment, and employees are eligible for 2 programs. One program uses life events, so we will obviously use the Open life event for enrollment into that program. We have a separate one for benefits in which the employee can make changes at any time. Two of these plans are Reimbursement Accounts for Parking and Mass Transit, which, like Health Flexible Spending Accounts, require re-enrollment every year. If our enrollment period is from mid-June to early July but changes aren't effective until August 1st, how can we make sure that the coverage and rates for these unrestricted plans