Mixing overwrite with formula

Hi-- so, I have a wonderful formula in a cell whereby depending on the dropdown choice selected in another cell, X, Z, Y occurs in the cell where the formula resides.

What concerns me is that sometimes a situation may occur where overwriting that formula is temporarily necessary. But we don't want to lose the formula there forever. Once one of those dropdown choices gets selected again, we'd like it to reassert the formula.

Any way to do this? Can I have a cell at the end of the spreadsheet, for example, that says:

=IF([Eval Interview Status]1 = "Pending", [Next Client Contact Deadline]1 = "[Referral Date]1 + 2")

whereby if Pending gets chosen from the dropdown of one cell, the referral date + 2 gets applied to Next Client Contact Deadline. And then we could overwrite in Next Client Contact Deadline. But if we re-select Pending later, the original formula re-applies???