Lol. Do not try to let go of the dead aide, and then call it?
Or you can:
1. Let your companion go sell your junk (you can type /selljunk)
2. Summon another companion and then the dead one again
3. Just press the summon button at the right bottom of his avatar.
This belongs in the guide section, in no way is this an exploit.
"A friend in need is a friend indeed, but a friend with weed is better"