Panther tank keeps original weight

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Historically, the Panther have had some reliability issues, despite using the layout the German FV industry was well familiar with. Those issues were more or less cured in a reasonable time. Going for an all-new system would not make it easier.

The drivetrain was layed out for a 35 tonne vehice, the Panther became a 'tad' heavier. They couldn't produce sufficient complex final drives capable to cope with the increased weight (as used in the Tiger series) so they had to stick with mass-producable less reliable final drives. They improved over time but stayed weak.
If they had opted for a rear drive in 40/41 they could have fixed this during development.

Denniss said:

The drivetrain was layed out for a 35 tonne vehice, the Panther became a 'tad' heavier. They couldn't produce sufficient complex final drives capable to cope with the increased weight (as used in the Tiger series) so they had to stick with mass-producable less reliable final drives. They improved over time but stayed weak.
If they had opted for a rear drive in 40/41 they could have fixed this during development.

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No, the chassis was designed around a 30 ton chassis and the first production model Panther weighed in at 43 tons, 13 tons over spec. The title of the project indicated what the weight was intended to be: 30 tons for VK30.02 (and .01). It was supposed to be able to handle up to 35 tons, but no more. They took the VK30.01 chassis, changed the armor layout and track width, added a heavier, larger engine, and several other tweeks, slapping a VK3601 (or perhaps VK4501) turret on the chassis, which was poorly laid out and too heavy, and then added even more armor on it.
https://de.wikipedia.org/wiki/Panzerkampfwagen_V_Panther#Technische_Daten
The final model, the G-series, ended up weighing in at nearly 45 tons after fixing some of the mechanical issues. Part of the issue with the final drive was that there wasn't enough room to insert a bigger, stronger one, so they had to use what was available given the time constraints and the war situation.