If I continue ignoring the wrong behavior by the tenant, this behavior will continue and escalate.

In the eyes of the law ignorance of your legal responsibilities to the tenant is typically no defense in court.

A good lease will have terms that require the tenant to notify the landlord immediately when any leaks or hazards are observed, and it will hold the tenant liable for damages that occur as a result of the tenant not notifying the landlord (for instance, if a toilet were leaking and flooding the bathroom, and the tenant didn't notify you for 5 days, and all that water seeped into the subfloor and caused rot and mold, you could potentially hold the tenant liable for their negligence--and have them pay not just to fix the toilet, but also to fix all the damage that could have been prevented if they had notified you quickly).As for your question about renewing their lease...This partly depends on whether you feel like they were negligent...for instance, if the water heater leak was easily observable, and you think they were negligent in not notifying you quickly, then that suggests they'll continue to be negligent and incompetent in the future--which puts you and your property at risk (a tenant who is so negligent that they don't report an obvious water leak is probably also negligent enough to leave the stove on, leave the doors unlocked, ignore fire hazards, etc., not replace smoke alarm batteries, etc.).   

This is the simplest method, but it also means your tenants are more likely to abuse the utilities by leaving windows open with the heat or A/C running, leaving lights on, ignoring the toilet that constantly flushes on its own, etc.3.

So I would ignore it.

You'll quickly learn whether they've been ignoring you on purpose or if they are just innocently forgetting to reach back to you.

I feel your pain...knowing that I can always make more money but I can't make more time, I block, ignore, and leave those calls behind. 

They ignored the letter and made no response. 

Even when you give her an ultimatum and demand she move out, she ignores you and keeps doing what she wants to do.I recommend you hire an attorney and let them handle ALL communication.

As you've probably learned over the years, ignoring problems doesn't work.