Some items are auto-loading, which means you keep them after reboot. The Hitchhiker's Guide To the Star Wars Universe is an example. At some point in time, you may lose one or more or your autoloading items. If this occurs, you can replace most items yourself:

Item How to replace...
SVS ship card'cardme' at Erving on SVS
Mickey Rukh Hatvisit quest's starting point
wedding ring'pick out replacement band' in Wedding Ring shop on Ryloth
team insigniapurchase in rebel/imperial team room
clan item'refit' in clan HQ
temp HC Knifeobtain from quest's starting point
HM beeper'beeper me' in HM Lounge
electronic thumbVisit the build room for your villa*
HM ammobeltvisit quest's starting point
HM slicertoolvisit quest's starting point
HM scientist kitvisit quest's starting point
JM sabervisit appropriate Jedi Master
diplomatic pin'receive reward' at terminal in diplomatic building

If you can't remember which planet your villa is on, visiting any villa build room and attempting to build will tell you where your villa is located.