It's always a pain. Death. You lose almost all your stats and lp, have to re-learn and re-discover everything just to get back to where you were, and still have to re-do all the credos you just lost.
I have 2 possible solutions to the problem at hand:
1) When you are creating a new character, and you have chosen to inherit an ancestor, a window pops up, showing all the credos that ancestor has gained, and (x) of the total lp that ancestor has collected during their lifetime. This lp can be spent to re-gain their lost credos. 10k lp can be spent for 1 credo, 20k for the second, 30k for the third, and so on and so forth. You still need to get pre-requisites in order to get higher tier credos. (x) would be how much lp you would get from your ancestor at the time of character creation, so it would be 10/30/40% of the ancestor's lp.
One problem with that is that hermits would be screwed, since they wouldn't have anyone available to bury the body, so they would be missing out on re-gaining multiple, if any, credos. Therefore, my second solution:
2) Using an ancestral shrine, you can spend 10 numen points to regain 1 credo. 20 points for the second credo, 30 for the third, ect.