The answer to that question is complex. The IRS has recently issues a series of updated repair regulations that deal with that topic. Depending on the cost of the repair it would be depreciated separately or treated as an expense. If the repair exceeds the lesser of $5,000 or 10% of the value of the asset, it should be capitalized and depreciated. Otherwise, it is probably an expense. This is a very simplified answer to a complex problem, but it may point you in the right direction.