The Raise Dead spell bestows 2x permanent Negative Levels. These do not have the usual 24 hours until you can Save roll against them or, in case of the Dhampir, remove them without a Save roll.
The Resurrection spell bestows only 1x permanent Negative Level.
The Restoration spell removes all temporary / 24 hours Negative Levels OR - it doesnt do both - removes 1x permanent Negative Level. After casting Raise Dead you need to cast 2x Restoration on that character to get rid of its 2x permanent Negative Levels from Raise Dead.
The Greater Restoration spell removes all temporary / 24 hours Negative Levels AND all permanent Negative Levels. If you acrued enough permanent Negative Levels, casting Greater Restoration is preferred.
There should be a tooltip behind the icon of your acrued Negative Levels that should tell you what their timers are, either something <24 hours or “Permanent”.
The system at hand is hard to understand. I needed to look through the rulebook to list the above infos, they are not very obvious. IMO, casting Resurrection over Raise Dead should just return the char with full HP instead of 1 HP and/or Id only use temporary/24 hours Negative Levels for really everything that causes them.
For the topic at hand, the Dhampir cant remove permanent Negative Levels. Getting your chars - ncluding Dhampirs - killed often and raising them really cripples you, much more than most enemy abilities could.
For instance, the 9th Level Wizard spell Energy Drain doesnt immediately bestow permanent Negative Levels. You need to fail against the Save roll against the temporary/24 hours Negative Levels to get them permanently. Permanent Negative Levels are the worst possible ailment you can get.