A prospective Buyer is likely looking for a place to move in with their family, and if you have a long term tenant in place with no future vacate date, then you are really limiting your buyer pool, and effectively running down your sales price. 

By the time you add in ice&water shield, vents and supplies, you are close to $250 / square in materials alone.

Does it have city water/sewer?

We have done about 18 units out of 36 along with the outside and are currently working on the pool area and landscaping.

Is the roof updated, and are there modern electric wiring and new water pipes?

Now she complained the issue of toilet fill valve which caused unreasonable high water bill and claimed it belongs to wear and tear and a plumbing issue.

If not, I would go closer to water, but not on top of it.

The other option is a water tank.   

I look at the BP video taking about the 50% rule and that is completely blown out of the water with newer construction

Roof, swimming pool, interior, exterior, driveways, landscaping, etc.