Are religious supplications (ibtihalat) bid'ah (innovation), and why?

If the intended meaning of religious supplications (ibtihalat) is the innovated celebrations, such as the Mawlid (Prophet's Birthday) and Laylat al-Isra' (Night Journey), then it is a rejected innovation (bid'ah mardudah); because the Prophet (peace be upon him) said: "Whoever introduces into this affair of ours that which is not from it, it is rejected." However, if what is meant by it is sitting in circles of remembrance (dhikr), knowledge, and admonition, then it is among the recommended acts.