I believe that when you take a rental property out of service its a disposition, and when it is place back in service the depreciation should be restarted at 27.5 years, and also be subject to the lower of cost basis or FMV test.
I have never seen specific guidance on the subject, the regs that deal with it - 1.168(i)-4 do not specifically cover former business property converted to personal use and then converted back to business, but I believe the plain language of 1.168(i)-4(b) which states that:
upon a conversion to business or income-producing use, the depreciation allowance for the year of change and any subsequent taxable year is determined as though the property is placed in service by the taxpayer on the date on which the conversion occurs.....The depreciable basis of the property for the year of change is the lesser of its fair market value or its adjusted depreciable basis (as defined in § 1.168(b)-1T(a)(4))
https://www.law.cornell.edu/cfr/text/26/1.168(i)-4
Suggests that the recovery period should start when the property is placed into service, and subjects the depreciable basis to a second test which would not be met if a previous depreciable period was resumed.
I would be happy to be corrected on this, if anyone has a source.