I performed ablution for Janaazah prayer, can I perform another obligatory prayer with the same ablution, like Maghrib prayer for instance, or I am obliged to renew my ablution?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

If you performed ablution and performed Janaazah (i.e. funeral) prayer, and your ablution was not nullified, then it is permissible for you to perform as many prayers as you like, and you are not obliged to renew your ablution according to the consensus of  the scholars. 

Allaah Knows best.