There are actually several software soft reset utilities. Software 309 has one called Warm Reboot; Philippe Majerus has one in one of his Windows CE software tools packages
(I believe it's the PHM Plus! pack
); there's a "Warm Boot" button under the System tab in Wolfgang Rolke's ResInfo. All of these have ARM versions. However, some devices don't support software soft resets, so don't get your hopes up.