Yes, you are required to report this in Iowa.  I was able to find the screen for you (I have included a screenshot below).  State programs are more difficult to give navigation instructions, but the screen for entering your Federal tax refund from 2015 came after questions asking about "Any Other Business Adjustments to Income?", "Do you have any capital gain deductions to report?", "2015 Iowa Tax Return", and then you should get the screen below entitled "Enter your Federal Tax Info."  If you hit questions about Iowa Federal Itemized Deductions and School District Taxes then you have gone too far.

Thank you!  I was actually able to clear it up before I saw this answer based on a different response I found online.  For some who are still struggling, when it asks, "Were you required to file a state tax return for 20xx?" and you say yes, leave BOTH boxes below blank.  If you click on either one, you will not be able to enter the refund information as required on line 27.  Leave both blank and click continue and the above screen shot will come up.  Good Luck!