It all depends on what
you want, and as others have said, that's a personal decision we can't help with.
You could sell it, miss it, and then buy another. But that other could have been mistreated and be a heap, or as loved as yours has been.
If you don't need the money and are going to enjoy it, why sell it?
If you need a lighter bike and can't afford both, sell it and get something else.
The way I feel at the moment, they can have my motorcycles after they've cremated me, but people change and one day I might decide to sell all my bikes and bits. I'm more likely to spontaneously change into a 6'4" daffodil though.