I'm confused. I know about Linpus Linux, but, Googling Limpus Linux gives me hits with Acer Aspire, but, in the body of the articles, refers to Linpus Linux, in multiple articles.
Linpus itself has very few releases:
But, none of their releases match the version that the OP has mentioned.
I would conclude after Googling a bit more that the laptop was given the name Limpus, but used Linpus Linux. Well, how can Acer make it more confusing?
If you go to one of the Linpus apps, like the terminal app, or the editor app, and hit the help button. Look for "About Linpus" as one of the choices. In KDE I can go to kwrite, for example, and can see "About KDE" as the bottom choice. Go into that choice, and see if you can find the Linpus version number that you're running. That will give us an idea as to how old or obscure the version is.
As far as updating. There is a PDF that tells you how to update from Linpus Lite 1.6 to Linpus Lite 1.7 at this link:
One would have to know if the version you're running is capable of being upgraded without jumping through hoops. From the pdf, it seems that they are asking you to back up your files, then do a re-install. That is, if the OS on your Acer is Linpus, or some variant named Limpus.