If a home sells or increases in market values.

If you are an electrician and you charge $75 an hour nobody would chastise you for turning down a job offer from a customer who wants you to work for $12 an hour.

@Ivan Barratt - what is your plan to increase the cash-on-cash returns?

Rich Dad's Increase Your Fiancial IQ by @Robert T.

Tenants that are one flat tire away from missing rent will not result in quality cash flow, and yet ironically these type of tenants are the kind that tend to rent in the type of neighborhoods that show the highest pro forma cash flow projections on paper ... too bad those cash flows aren't what you will actually get during a downturn, and you spend much of your time chasing down rent as opposed to growing your portfolio ... too bad that the increases in rents and prices will not tend to keep up with inflation in many of these neighborhoods too ...

With anything old, it's bound to be an onion of problems to replace, so unless it is necessary to replace it, I would not touch it.On the other hand, if everyone else in the neighborhood is updated high efficiency, then that's another story and it makes your house somewhat deficient.Not sure how you get from a $2K replacement cost to $6-10K value increase.

Or admit more students, both of which increases revenue. 

I am laser focused on  educating myself about analyzing opportunities to increase knowledge and decrease hesitation that results in missed opportunities. 

I then got my credit limit increased because of on time payment and my score really jumped from there.

With an increase of about 7% over last year in Denver (https://www.cpr.org/news/newsbeat/colorado-springs...) and no contraction in sight, scheduled rent increases should continue to multiply that $2,600 of mailbox money forever more, or at least until your portfolio review.