Should I upgrade a rental property if there isn't much upside?

[Vierra Wong]

We have a small multi-family apartment building in a prime location.  The apartments have historically rented out easily because of the location despite the 70's look of the place. We have a tenant moving out in a couple months. Everything is in working order. My question is should I spend money to upgrade the unit (double paned windows, new flooring, re-do bathroom) if there is not that much upside in rent? It would show better and potentially rent out more quickly, but is it worth the cost if my rent can only increase by about 3%? Thanks in advance!