@Ayyoub Reza it's a good thing you're asking this here so you don't run afoul of the law in Michigan. 

It's a pain, but its probably a good requirement to ensure everyone has a basic understanding of the law.  

@Deinno OKeefe, unless your duplex was built in 2009 or later, or unless you live in the other unit, it is still subject to statewide rent control (the law known as AB1482).You're limited in how much you can raise this tenant's rent every year -- either 10% or 5% plus the percent change in cost of living.

The tenant kept bothering me about a lot of repairing issue.

Quote from @Joseph Milano: I would talk to the renter to see what they want to do.The easiest method is to get tenant's permission to apply the funds toward their next month of rent.If they prefer the money back, I would issue them a check, money order, or cashier check when they sign the new lease.

One of my issues is I am not sure what the neighborhoods are like at the properties I find on-line.  

Where I had issues was during construction and getting the checks from the lender.

The issue is housing, housing is 1/3 of CPI and inflation is floating at or above 3.

So, if your bathroom was un-permitted you may be required to remedy that issue with this renovation.

Since I am doing the work, I have no quality issues and believe in doing the job right.