I don't re apply glue to the base tape of a previously glued tubular when re applying. Just the rim. Also I only apply one base layer to a new rim so only 2 coats in total. No problems yet but I don't race and don't really push the adhesion to it's limits.
Either rim side or base tape side should do in this case.
But why only one coat of cement on the rim? The base layer serves as an anchor for the second layer to attach to. Without it the entire job is compromised even if you don't race.
Surely the little extra cement isn't taking too much effort to put on?
A glue job well done makes an awful lot of difference. Not just safety wise but in Crr as well. If you never experienced the difference you should try it out. It is well worth the extra time and effort.