Mount new ~ to old one in another partition

[Roy]

These are all good solutions 
Maybe next time I ran into this problem I'll have more options to pick  ;D

[kpanic]

Ooops! Actually [member=458]m654321[/member] and [member=7644]DeepThought[/member] gave better instructions.
Better NOT copy the old configuration files and directories, which usually begin with a dot,
like for example the directory ~/.synaptic

So, better just copy (or link) the normal directories like ~/Documents, ~/Music and so on