Sergii
I don't know the API that you are using - you will need to read its documentation or check its implemention. If it doesn't support the pre-scaler setting you can simply do the following (after you call the setup).
1. Disable the LPTMR with LPTMR0_CSR &= ~1;
2. Set the pre-scaler value you need (assuming LPO clock)
LPTMR0_PSR = (LPO_CLOCK_SOURCE | (DIVIDE_VALUE << 3));
3. Re-enable again LPTMR0_CSR |= 1;
where DIVIDE_VALUE is 1 for divide by 2, 2 for divide by 4, 3 for divide by 8, 4 for divide by 16 etc.
This will then increase the timeout value that you set by this factor.
Regards
Mark
uTasker developer and supporter (+5'000 hours experience on +60 Kinetis derivatives in +80 product developments)
Kinetis: http://www.utasker.com/kinetis.html