Is there a move or ability the wont let you lose your item of so ething?

Question

This is what I have in mind I have a agua berry right I want to keep using it is there Althing other than recycle and harvest to help with this

Answer 1

No, there is not another item regenerating move/ability other than Harvest/Recycle.
Source: Experience (I would have heard of it by now :P)

However, you tagged "Mew", so if the Pokemon is Mew, it learns Recycle in Ultra Sun/Ultra Moon via a move tutor.