It went with out water for about a month or so. I've started watering it regularly making sure to not over water it but it keeps getting worse im gonna add nitrates to the soil. No pests as far as I can tell.. Im wondering if re-poting it is a good idea or if its just gonna put it under more stress. Any tips would be appreciated :)
P.S. its my grandma's and she has passed so I would very much like to keep it alive.

If you are watering and the leaves are not perking up, the roots are dead. Your best bet is to take cuttings and grow some new plants. I bet @purpleinopp knows how to do that. I suspect she won't see this until tomorrow.

The last thing it needs right now is fertilizer. Don't do that.

I agree with Lucy, feeding a stressed plant will only cause more problems. I also think the roots are the problem.

Dear friends, if you don't tip the plant out of the container and look you will never know what state the roots are in. Very gently tip the problem plant out of the container and look and see what's going on in the root mass. Make it a practice to always look at the roots of any plant you can pick up by hand. If you watch closely you can see if the plants is getting enough or to much water. Most common problems stem from water management issues and if you get the watering down correctly you won't have problems.

We don't need to see the roots to know they are compromised. Sometimes, you can just read the plant.

I know my plants need a drink if their leaves lose turgor. If I water and it's still wilted, I know it has a root problem. No need to tip it out of the pot.

Hi & welcome! You mentioned it went without water for a month. Did you soak it thoroughly after that? Scheffleras do not like dry soil, but could, as mentioned above, recover if the roots did not get so dry that they are dead. No harm in soaking it again & waiting longer. It might take several applications of water, several minutes apart, to thoroughly moisten very dry soil.

The tree could still be alive even if all of the leaves fall off. If you nick the bark with a fingernail & it's green under there, don't give up. Just add water again when the pot feels more lightweight than when it was thoroughly soaked.

I've had excellent luck with cuttings rooted in water & then potted, and with those stuck directly into the soil. Starting with dehydrated material, I'd probably lean toward water, but you have enough material there to try both ways. I'm not sure this plant is still viable and able to propagate, but encourage you to try.

It's good that people are aware of "overwatering" but people who are concerned about that rarely kill a plant that way. It takes some effort, not counting plants from naturally very dry climates. It's equally distressing to a thirsty plant like Schefflera to have really dry soil.

Thanks for the mention, Lucy : )