i gave it a change about a week ago and im going to give it one tomorrow ,i do have a thermomiter and its about 16 and with the live plants they keep dieing and the little guy (but its a girl) has a fetish of digging.
Have you tested the water for ammonia, nitrite, nitrate, and pH? If so, what were the results?
You need to be doing
DAILY partial water changes. These water changes will help dilute the ammonia to acceptable levels for the axolotl that has to live in this water.
The water quality is the most important thing to an axolotl's health and well being. Having good water quality will ensure your axolotl lives a long and happy life. Poor water quality will make the axolotl quite sick, and will very likely kill him.
Remove the dead plants as this rotting matter will be contributing to the ammonia levels. If dying, the plants are doing more harm than good, and should also be removed. If you can't keep the plants healthy, take them out of the tank.
If the axolotl is still being kept on the gravel shown in your avatar, I would strongly recommend you remove it. Axolotls are opportunistic feeders and will snuffle through the substrate at all hours looking for food. Gravel of that size can (and will!) easily be ingested by mistake, and this can kill the axolotl.
Trapped muck under the substrate will also wreak havoc with the water quality if not removed promptly.