Welcome to the forums, newcomer!
You're advised to replace the thermal paste as soon as you break the mount/contact between heat source and the cooler's plate. When you reuse thermal paste that was already applied on a heat source, you introduce airgaps.
sitting at 50-70 celsius while idling, while gaming it goes up to 85-95
We can't tell you much unless you state the make and model of your processor. For better context, please state the full specs to your system. Mentioning ambient room air temps also helps.