I took early retirement, using widow's benefits at a loss of 20% of the monthly check.
With the cost of EVERYTHING skyrocketing, can I get that 20% back w/o it costing an arm and leg?
It sounds like you could withdraw your application and reapply at a higher monthly rate, but you'd have to repay all of the benefits you've received to date in order to do so. If you were receiving retirement benefits rather than widow's benefits, you could only withdraw up to one year after your original month of entitlement.
Before doing anything further, you may want to run the maximization software available on this website. If you are eligible for benefits on your own record, withdrawing your application for widow's benefits may be disadvantageous. The software should help you determine your best course of action.