The RAN says that it is better to use a PESACH rather than CHAROTOH where the neder was to do a DVAR MITZVOH because CHAROTOH would be the equivalent of TOHEH AL HORISHONOS.
1-Why can't one have CHAROTOH on the NEDER alone without having Charotoh on the MAASIM TOVIM as we say by HATORAS NEDORIM on EREV ROSH HASHONOH?
2- PESACH is also OKER the NEDER L'MAFREOH.
Yaakov Shapiro, Brooklyn, NY, USA
(1) (a) See the Machaneh Efrayim (Nedarim #16) who proves from our Ran that if someone makes a Neder to fast for a certain number of days and then regrets his Neder but does not regret the days that he has fasted, this is not considered Charatah. The Machaneh Efrayim writes that the "Mussar writings" which state what we say in Hataras Nedarim on Erev Rosh Hashanah - that we do not regret the good deeds but only regret that we did not accept them upon ourselves with the words "Bli Neder" - are only referring to someone who thinks he has transgressed on his Neder. For such a person it is sufficient to have Charatah merely on the fasts that he did not fast because he would not have made the Neder in the first place if he would have known that he would later transgress the Neder. Therefore this sort of person has a Heter for his Neder through a Pesach not through Charatah. If the Heter is through a Pesach it is not necessary to regret all the fasts, only the ones that he did not observe.
(b) The Imrei Binah Yoreh De'ah (Dinei Nedarim #18 DH v'Od) writes that one is not forced to accept the Machaneh Efrayim's position, because one could say that the reason Rav Sechora did not want to have Charatah on the Neder alone is because he wanted that all his fasts should remain with a Kabalas Ta'anis (i.e. since the Gemara Ta'anis 12a states that any Ta'anis which a person did not accept upon himself before the night of the fast is not considered a Ta'anis, it follows that if Rav Sechora would lose his Neder he also loses all the fasts). The Imrei Binah also cites the Teshuvos Chavos Yair (end #29), which is also cited by the Gilyon Maharsha on Shulchan Arukh YD 228:7, that if someone makes a Neder to fast a certain number of days and afterwards has to annul the Neder for some reason, all the Berachos of "Aneinu" that he said in the Shemoneh Esreh of every Minchah before the Ta'anis, will be retroactively Berachos l'Vatalah (See also Birchos Avraham).
(2) The Ayeles Hashachar (by Rav Aharon Leib Steineman Shlita) explains ingeniously the difference that the above Machaneh Efrayim gives between whether the Neder was permitted by Charatah or by a Pesach. He writes (22b DH v'Hineh b'Ha) that when the Chacham uproots the Neder retroactively this does not mean that nothing was ever said by the Noder, but rather it means that he did say something, but what he said does not have any power to make anything forbidden. In contrast Charatah does not mean merely that the Noder became forbidden to do something, but rather he has to regret that he ever said his Neder.
Now the Ayeles Hashachar cites the Mishneh Berurah 562:39 that after Pesach and Sukos a Mi she'Beirach is made for anyone who accepts upon himself to fast on Monday-Thursday-Monday, to which the congregation answers Amen. When someone answers Amen this is considered that he has accepted the fast and it is not now necessary for him to accept it on the Minchah before the fast. However this acceptance is not obligatory
and since he did not say explicitly that he accepted the fast he is not required to fast if he does not want to. The Ayeles Hashachar writes that one learns from this that it is possible to have a Kabalah so that if he fasts it will be considered a Ta'anis, even though this Kabalah does not make him obligated to fast.
The Ayeles Hashachar continues that according to the above, if someone made a Neder to fast and then dissolved this through a Pesach, even though there is no Neder, nevertheless that which he said that he wants to fast is not erased. In other words the Kabalah still remains even though the Neder has gone, and he is not obligated to fast but if he does he will receive a reward. In contrast if he had Charatah, this means no Neder at all remains so he will no longer receive any reward for his fasting. This is why the Ran only writes that he will lose the reward of the Ta'anis if he has Charatah but not if he annuls the Neder through a Pesach.