Change part of an excel forumla to include data from another cell

I am looking for an easy way to replace part of a formula in Excel.

I have to do this for over 66,000 formulas every year. Currently i use Find & Replace to speed up the job but it still takes me several hours to do it.

='C:\Excel\[File1.xlsm]08-01-20'!V5

I want to replace the 08-01-20 part of the above formula with the value of cell C2