At very low levels or if a character hasn't been with the party very long, if it dies it's probably not coming back.
At mid-high levels or if a character has been around a while, if the party can get it back (assuming the player wants it back) they'll probably try.
Given the right payments in sacrifice (I don't use the silly diamond-dust thing; magic items, objects of value, or even simple gold will do) Raise Dead is usually relatively easy to find and becomes trivially easy once any PC Cleric gets to 9th. Resurrection can be somewhat trickier, involving more cost and often much more travel. Both spells are costly - usually around 6-7K g.p. for a Raise and nearly twice that for a Res.
As this is 1e, they have to make a resurrection survival % roll in order to come back; and they lose a Con. point. If you fail, I have a table of possible reasons why e.g. you've become an undead, a god says 'no', you've already been revived elsewhere, and so on. I've also recently instituted a second table for those who are revived, of things that might have happened to you while you were dead - you might pick up an affinity for or hatred of undead, for example; or come back with a quest sitting on you, or whatever - or nothing at all.
The resurrection survival % roll is a mechanic that really should be brought forward to all editions. Just the mere threat of failure and perma-death, even if a small threat, makes people much more careful with their characters (except my crew; they greet death like a long-lost friend) than if the threat was not there.
Lanefan