Does renoise already reset VSTi (resets VSTi’s internal LFOs etc.) when you play song from start or when you render the song? Resetting (reloading?) right before playing would result in the song playing same every time.
I have no idea, but when it comes to lfo, either Renoises or from vst(i), I usually double click in the values in the automation editor if I want it to sound the same always.
Thanks for the tip. I’ll try to change lfo speed in VSTi at song start and listen if it sounds the same every time.
There’s no way for Renoise to know what internal structure a plugin has, or what special functions need to be triggered during certain events, since the VST standard does not cover specialised objects such as LFOs - it only covers the most important basics that allow plugins and hosts to talk to each other. Everything else is up to the developer.
When the host needs to change modes, such as when changing from realtime playback to offline wav rendering, the host instructs the plugin to suspend its operation. Then the host provides the plugin with any new information it needs, such as a new sample rate, and then finally the host instructs the plugin to resume operation once again.
The suspend/resume period is usually when plugin developers will reinitialise important data, clear sample buffers, recalculate filters, etc. It is also a perfect place to reset LFOs and other modulations that we want to be predictable each time we render our song.
Whenever you render to wav in Renoise, or reload your song, or change sound card properties, etc., the plugin will be reinitialised in this way, and then hopefully the developer of the plugin was smart enough to reset LFOs there 
To be honest though, you can probably save yourself the headache and just use Renoise’s own native LFO Device. Connect the LFO to an Automation Device, and then connect the Automation Device to the parameters of the VSTi synth, and you will have full control over the LFO properties, while being able to reset it to any position at any time you want. If it’s a VST effect you’re working with, then it’s even easier because you don’t need the Automation Device, you can just map parameters directly in the Track DSPs area.