Reactivation Fee after Renewal time has past

Hi,
We currently are giving our members a grace period of a month but wanted to have the ability to charge anyone outside that grace period a $50 reactivation fee. This would be automatically added to the invoice if a member has let their renewal option pass.

Any help on how to achieve this would be greatly appreciated.
Thanks so much,

Best way to do that is probably using CBSubs Promotions and a negative promotion, which will increase the price instead of decrease. Example as follows.

Basic
Promotion Type: Applies to all purchases
The promotion is: A: A fixed amount A
Fixed Discount Amount in currency above: -50
Advanced
Which plans must be purchased at same time: SELECT_PLAN_HERE
Conditions
First condition: This condition:
Any of the following plans subscriptions: SELECT_PLAN_HERE
Must be in state: Expired

That should increase the cost of the selected plan by $50 if they've an expired subscription to it. Grace period prevents a true expiration state so this will work with grace period as well.