Can my ex wife ask for alimony increase through Nevada courts after 6 years? she lives in WI and I live in MO

As with many legal questions, the answer to yours is "maybe" -- depending on facts that you have not revealed. Normally, unless the court order indicates otherwise, alimony is "modifiable" -- it may be made shorter, or longer, higher, or lower.  One peculiarity of the Uniform Interstate Family Support Act (“UIFSA”) is that only the State which made an original alimony award may modify it — no matter how many years have passed, and even if all parties have left the State of issuance.  This makes alimony modifications follow very different rules from those relating to child support. So the questions are:  Is there an original order for alimony?  From where?  What does the order say?  Answer those questions and you should have at least the first answer you need -- whether your ex can make the request in a Nevada court.  As to whether it will be granted . . . well, that is a different question.