First of all, having a single link acting as VSL is not a recommended design. It is recommened to have atleast 2 links in the VSL and the links should terminte on 2 different chassis.
From
Recovery Actions
An VSS active chassis that detects a dual-active condition shuts down all of its non-VSL interfaces (except interfaces configured to be excluded from shutdown) to remove itself from the network, and waits in recovery mode until the VSL links have recovered. You might need to intervene directly to fix the VSL failure. When the shut down chassis detects that VSL is operational again, the chassis reloads and returns to service as the VSS standby chassis.
Loopback interfaces are also shut down in recovery mode. We do not recommend configuring loopback interfaces at this time (while in recovery mode), because any new loopback interfaces configured in recovery mode will not be shut down.
Note 
If the running configuration of the chassis in recovery mode has been changed without saving, the chassis will not automatically reload. In this situation, you must write the configuration to memory and then reload manually.
So to answerr your question
" so if we change the configuration in one of them that has mayor priority.Exist some procedure to re-activate the VSS link?or turn up automatically?"
Answer: No you cannot turn it up automatically
