X-plane is resource hungry so the more RAM you have and the faster the RAM the better off you will be.
However, RAM is only one of a few items that need to be considered to run X-Plane.
Have you looked at the system requirements for X-Plane. The details can be found at http://www.x-plane.com/kb/x-plane-11-system-requirements/ Most flight simmers wanting to acquire a new system are going for the recommended requirements and even higher specifications.
You have indicated that you would consider a new laptop. If you go for a laptop you need to ensure it is a "gaming unit" which are purpose built to cope with products like x-plane. One issue with a laptop is you need good cooling as the hardware creates a lot of heat. Another issue is that just a laptop screen gives you poor rendition unless you connect an external screen (refer to an earlier question in this forum). Most gaming laptops have a 17 inch screen.
Stay away from the "fruit systems" ie Macs, as what you will spend on a good gaming laptop will be less than a high spec MAC laptop. Although X-Plane is developed using a Mac system one of the Laminar Research members has recommended the purchase of a purpose built PC as a betters system choice.
My suggestion would be to keep your current laptop for your other computer "needs" and invest in a "purpose built" PC machine based on the recommended system requirements. Most likely a Windows based operating system. In going this way you should get a high end machine at a lesser cost and you can invest in a system that is affordable to you. In addition as time passes you can upgrade components as and when needed or afforded whereas if you go for a laptop or MAC PC then any upgrades are virtually impossible as they are "sealed" units. RAM would be the only upgrade.
Whatever you purchase go for NVidia cards and not in SLI as X-Plane cannot handle SLI. NVidia cards have always given a better outcome/performance than AMD cards. AMD style cards have had problems with the latest versions of X-Plane as indicated in earlier forum problems/questions.