Was the upgrade from 6.x to 7.5 done recently? If so, it sounds like you skipped a known issue that happened in 7.2.
It's documented in this KB article:
http://www.airwave.com/support/knowledge-base/?sid=50140000000adZE
I've never tried to run the fix on 7.5. If you've already moved a few APs, then the above fix won't work. This is probably something that can be better handled in a support case, but here's what I'd do to get the placement back:
I'd find an old backup from 6.x. Install the matching version on an extra server (for temporary use) - we'll refer to this server as New-AMP. Restore the backup on New-AMP. Upgrade New-AMP to 7.2 following the upgrade steps. Run through the fix from the KB article noted above on New-AMP. Verify placement after going through the fix on New-AMP. Upgrade New-AMP to 7.5 following the upgrade steps. Double check the VisualRF on New-AMP. Take a VisualRF backup from New-AMP. Then delete the floor plans on the current-AMP. And restore the fresh made VisualRF backup from New-AMP on current-AMP.
Otherwise, the alternative is to manually move all APs on each floor plan.