The correction principle is to put the plan in the same potion had the error not occurred.
So if, say, when the $100,000 was liquidated, 25,000 shares were sold. If it only takes $95,000 to repurchase those shares, then so be it.
Tougher to calculate though, are investments that pay dividends or capital gains directly to the plan.
What happens if those 25,000 shares were sold in September and 250 more shares would have been added to the account as a capital gain on December 28? Should the particiapnt be required to re-purchase 25, 250 shares (regardless if the share value went up or down)?
I guess that's why it's acceptable to use the plan's rate of return instead of the exact gain/loss...